Ensure make distcheck actually passes (and make clean)

Originally we generated all compiled resources within the data/ build,
which in fact broke the dependency chain within autotools due to relative
paths.
With this commit, each directory (build stage) now builds its own resources
which has the effect of ensuring make distcheck passes, and make clean. This
should ease package maintainence for other distributions somewhat.
budgie-plugin: Ensure comments are consistent with API
session: Ensure all files are included so distcheck doesn't bomb
Inroduce Panel Editor

Introduces a somewhat unoptimized way of editing the panel layout. Note there
is currently no shortcut for accessing this editor, so it is still in effect
hidden from the user.

The Panel Editor is simply the beginnings of a new management UI to allow
dynamic positioning, adding and removing of applets. It has a lot of work
to go through before it will be considered stable.
Merge remote-tracking branch 'origin/cleanup'

Conflicts:
	panel/Makefile.am
panel: Enable launching preferences dialog via panel right click menu
Update README
panel: Add initial GNOME Panel theme support

This works on an extremely simply premise which thus far seems to work quite
well. The vast majority of themes that tailor to GNOME Panel explicitly use
"PanelToplevel" and "PanelApplet" types to do so. We simply take advantage
of this by using a PanelToplevel (inherits from BudgiePanel) and wrap all
applets in a PanelApplet class (an empty Gtk.Bin)

This setting is only read once, at panel start time. You still need to restart
the panel for the setting to take effect.
panel: Add new "Workspaces" (Wnck.Pager) applet
panel: Pad the tasklist widget a little
panel: Tweak gnome-panel-theme-integration further
Update README (todo item)
panel: Remove debug statement, no longer needed.
data: Use correct names in layout.ini
wm: Use braces.
applets/budgie-menu: Fix missing search results

This fixes a silly issue where we didn't store the lowercase variant
of our search items from down() and broke the majority of search results.
applets/budgie-menu: Reload menu tree upon changes

This ensures we keep our tree data up to date with what is actually present
in the gnome-applications.menu directory whenever it is changed, i.e. when
a package is removed/updated/reinstalled, etc. This also stops the panel from
crashing any time .desktop files are modified, as well as the nasty (null)
labels previously seen.

(Or, this should've been re-implemented back at the vala rewrite..)
widgets: Remove defunct C integration for BudgiePopover
widgets: Do not attempt to quit main loop from BudgiePopover..
panel: Add more options to Editor, turn it into a proper dialog

This is a bit of a mini UI overhaul, just making the panel editor look more
like an actual dialog (By using Gtk.Dialog, whodathunkit) and *slightly*
more HIG3 (GNOME) conformant. Not completely, because it looks like crap.

This commit also brings in the gsettings based options, i.e. size, location
and gnome-panel-theme-integration.