Prevent criticals when initializing a Wayland display

When we call _gdk_wayland_display_load_cursor_theme during
the initial opening of the first display, gdk_setting_get does
not work yet, since it relies on the default display/screen
being set, which only happens after open returns.
Instead, just use the screen of this display.
Add some more GtkWindow tests

These tests check that a toplevel window ends up with the expected
size after setting default sizes or resizing. It currently passes
on X, but fails with client-side decorations under X and Wayland.
Some window size test tweaks

Draw a checkerboard pattern, and add an interactive mode that
waits for events before moving on. This makes it easier to see
when a size is wrong.
window: handle titlebar property for the buildable interface
Always use gint for border_width

This avoids an evil trap when doing MAX (..., ... - 2 * border_width)
and the expression on the right gets promoted to unsigned, instead
of going negative as you would expect.
https://bugzilla.gnome.org/show_bug.cgi?id=699633
Updated Tajik Translation
GtkTextView: add some FIXME and TODO comments
Add boolean return value for gtk_text_tag_table_add()

https://bugzilla.gnome.org/show_bug.cgi?id=614717
gtk_text_buffer_create_tag(): return NULL on failure

https://bugzilla.gnome.org/show_bug.cgi?id=614717
Fix gtk_text_iter_forward_to_tag_toggle() for end iter

The function must return TRUE only if there is a tag toggle _after_ the
iter, not _at_ the iter. So for the end iter, the function must always
return FALSE.

Add also unit tests for gtk_text_iter_forward_to_tag_toggle().

https://bugzilla.gnome.org/show_bug.cgi?id=691266
textbuffer: fix selection replacement when pasting

It is more logical to first delete the selection and then pasting the
text. When the selection and the text contain tags, the new behavior is
more natural.

A segfault in paste_from_buffer() is also avoided. The segfault occurs when
the text to paste is deleted because it is the selection.

https://bugzilla.gnome.org/show_bug.cgi?id=339539
gtktextchild: replace hard-coded values by a macro

The macro already exists, so it's better to use it.
Doc: various small fixes