Clean up code to find themes

Simplify code to find the right theme to load and loading it by
moving all the loading code into a load_theme() helper function,
and making meta_load_theme() use that as it searches through the
directories.

Look for old-version themes even when loading relative to the
working in debug mode. Don't unnecessarily duplicate and then free
info->theme_file and info->theme_dir.

http://bugzilla.gnome.org/show_bug.cgi?id=592503

NOTE: Patch copied from mutter and adapted for metacity.
metacity-theme-3.xml: Add a flexible version mechanism

The current mechanism of metacity-theme-1.xml and metacity-theme-2.xml
is not flexible for allowing small-scale additions. With this patch
we bump the major version version once more to metacity-theme-3.xml
and add a single feature:

Any element in the DTD can have an attribute:

 version="[<|<=|=>|>] MAJOR.MINOR"

And it will be ignored unless the predicate is met. (< and > should
be to be entity escaped as &lt; and &gt;)

This allows having alternate sections of the theme file for older and
newer version.

* Required GLib version is bumped to 2.14 so we can parse versions
  with a regular expression.

* We switch internal version numbers to be "1000 * major + minor"

* We keep a stack of the maximum required version for the current portion
  the XML tree so that the "cannot use versions you don't require" stricture
  of the old code can be made local to a subpart of the tree.

* A version on the top metacity_theme element causes the entire file to
  be ignored; this allows having one metacity-theme-3.xml for version 3.2
  and newer (say) and a metacity-1.xml for everything old.

Actual new features will be added starting with 3.1 - 3.0 is just the
version="" feature.

http://bugzilla.gnome.org/show_bug.cgi?id=592503

NOTE: Patch is copied from mutter and adapted for matacity.
Add frame_x_center/frame_y_center variables for themes

Sometimes you want to position something (usually the title) to be centered
with respect to the entire frame instead of centered with respect to the
individual piece currently being drawn.

This patch adds frame_x_center and frame_y_center variables that represent
the X/Y centers of the frame in the coordinate system of the piece being
drawn.

The theme version is bumped from 3.0 to 3.1 (3.0 is just the new version
system, 3.1 will have all the features we add for Mutter-2.28.)
position expressions

https://bugzilla.gnome.org/show_bug.cgi?id=591842

NOTE: Patch is copied from mutter and is adapted for metacity.
Allow a theme to specify ellipsize width for a title

It's nice to indicate when a title is truncated with an ellipsis.
Because themes may draw a title multiple times to draw a shadow, or
may include the window icon within the title area, we can't determine
the proper ellipsization width automatically, so add an optional
attribute to the <title/> element "ellipsize_width" which, if set,
is the width to ellipsize at.

This is only enabled if a theme version of 3.1 is required.

When it's not set, we keep the old behavior of just letting the
title be clipped with a hard edge.

https://bugzilla.gnome.org/show_bug.cgi?id=591842

NOTE: Patch copied from mutter and adapted for metacity.
Add meta_window_get_transient_for() method

NOTE: Patch copied from mutter and adapted for metacity.
Optionally attach modal dialogs

Add a preference /apps/mutter/general/attach_modal_dialogs. When
true, instead of having independent titlebars, modal dialogs appear
attached to the titlebar of the parent window and are moved
together with the parent window.

https://bugzilla.gnome.org/show_bug.cgi?id=612726

NOTE: Patch copied from mutter and adapted for metacity.
Add frame type for attached modal dialogs

Add a new frame type META_FRAME_TYPE_ATTACHED which is used for
attached modal dialogs.

The theme format version is bumped to 3.2, and attached windows
can have borders defined in a metacity-theme-3.xml as:

 <window version=">= 3.2" type="attached" style_set="[name]"/>

If no style is defined for "attached", drawing will fall back
to the "border" type.

https://bugzilla.gnome.org/show_bug.cgi?id=592382

NOTE: Patch copied from mutter and adapted for metacity.
theme-parser: Use peek_required_version() for validation

When validating button functions and frame styles, the required
format version of the features used in the theme was compared to
the major version number of the supported format, limiting additions
to major theme format bumps.
Use peek_required_version() instead, so the minor version number
of the supported theme format is taken into account.

https://bugzilla.gnome.org/show_bug.cgi?id=635683
theme: Add background functions for single buttons

With the existing background functions, single buttons can not be
styled separately - on the left side, the style of the left button
is picked, and the right button's style on the right side.

As theme authors may want to add rounded corners to button groups
as a whole, it makes sense to treat the case of a single button in
a group differently.

https://bugzilla.gnome.org/show_bug.cgi?id=635683

NOTE: Patch copied from mutter and adapted for metacity.
theme: Add tiled_left/tiled_right frame states

It may be desirable for theme authors to treat side-by-side tiled
windows differently, for instance to give the edge-touching border
a width of 0, so add additional frame states for tiled windows.

https://bugzilla.gnome.org/show_bug.cgi?id=637330

NOTE: Patch copied from mutter and adapted for metacity. This adds
only description in doc/theme-format.txt as all other changes has
been added already.
theme: Allow using custom colors from the GTK+ theme

Add an additional color type to pick up colors defined with
@define-color in the GTK+ theme's CSS:

  gtk:custom(name,fallback)

(where "name" refers to the name defined in GTK+'s CSS, and fallback
refers to an alternative color spec which is used when the color
referenced by "name" is not found)

The main intent of the change is to allow designers to improve
Adwaita's dark theme variant without having to compromise on colors
which work in the light variant as well.

https://bugzilla.gnome.org/show_bug.cgi?id=648709

NOTE: Patch copied from mutter and adapted for metacity.
theme-parser: Look for themes in XDG_USER_DATA_DIR, not in ~/.themes

https://bugzilla.gnome.org/show_bug.cgi?id=675316
Make sure to always call va_end
Clean up antialiasing fixes

Simplify the code by noting that when we have square end-caps, the
results of generic line path give the right pixel-aligned rectangle
for horizontal/vertical lines.

Add comments and remove some extra braces.

https://bugzilla.gnome.org/show_bug.cgi?id=630426
Replace public MetaFrameGeometry with MetaFrameBorders

There were actually *two* MetaFrameGeometry structs: one in theme-private.h,
one in frame.h. The latter public struct was populated by a mix of (void*)
casting and int pointers, usually pulling directly from the data in the private
struct.

Remove the public struct, replace it with MetaFrameBorders and scrap all
the pointer hacks to populate it, instead relying on both structs being used
in common code.

This commit should be relatively straightforward, and it should not do any
tricky logic at all, just a sophisticated find and replace.

https://bugzilla.gnome.org/show_bug.cgi?id=644930

NOTE: Patch copied from mutter and adapted for metacity.
MetaFrameBorders: Add meta_frame_borders_clear

Just a quick little commit to help clean things up for when we add invisible
borders. Additionally, do a little housekeeping in preview-widget as well.

https://bugzilla.gnome.org/show_bug.cgi?id=644930

NOTE: Patch copied from mutter and adapted for metacity.
theme: Allow disabling fallback colors in gtk:custom()

gtk:custom() requires a fallback color in case the GTK+ theme in use
does not define the desired color. As in general the fallback color
will approximate the intended color, there is the risk of typos going
unnoticed. To make catching these kind of errors easier, allow to ignore
the fallback color specified (and fall back to a nice shade of pink
instead) by setting an environment variable.

https://bugzilla.gnome.org/show_bug.cgi?id=656112
theme: Replace char array element comparisons with strncmp

https://bugzilla.gnome.org/show_bug.cgi?id=662962
theme: Also support alpha values in blend/shade functions

This doesn't appear to be used currently, but fix it while at it ...