stock icons: print icons no longer fuzzy

- improve legibility by aligning to the grid
- less dramatic stroke around application-exit
docs: Add more a reference in GtkHeaderBar
Use 16px as default button and small toolbar icon sizes

https://bugzilla.gnome.org/show_bug.cgi?id=350190
gdk: enable rgba visuals by default

Unless GDK_RGBA=0 is set.

https://bugzilla.gnome.org/show_bug.cgi?id=630217
Improve docs for focus-line-pattern
resources: move resources into a subdirectory
Trivial formatting fix
Slight rewording of some docs
Add versioned dependencies in pc files

This helps with runtime deps between devel packages.
https://bugzilla.gnome.org/show_bug.cgi?id=722638
Fix gtkenums doc section
Build gtk-doc scanner without deprecation warnings

Use of deprecated symbols is expected in this code,
no need to warn about it.
Add an #ifdef to shut gtk-doc up

gtk-doc complains that the stock macros are deprecated,
but not in an #ifdef block. So add one.
Update Visual Studio Build Files

-"Install" the newly-added public gtkpopover.h
-Make the gtk3-demo projects up-to-date