Remove gnome-games high contrast icons

These are distributed by the games themselves, now.
Fixup Makefile.am after last commit
buttons,checkboxes have a :checked state now

https://bugzilla.gnome.org/show_bug.cgi?id=733967
HC: sync linked button fixes with Adwaita

https://bugzilla.gnome.org/show_bug.cgi?id=733979
use new radio/checkbox states from the icon theme

- opacity only has usability downsides. For more
  background info see https://bugzilla.gnome.org/show_bug.cgi?id=734290
prepare for 3.13.90 release
HC: make the SASS 3.4 parser happy
HC: popover checkbox buttons fix

Last bit keeping https://bugzilla.gnome.org/show_bug.cgi?id=734945
open
HELL: adapt mutter theme to latest Adwaita changes.
Mutter: update backdrop window buttons color
Stop shipping out of date metacity-theme-2.xml
remove red dot placeholders

- fullcolor is still a better fallback than red dot
- many have been covered by rendered symbolic already

https://bugzilla.gnome.org/show_bug.cgi?id=735455
more red dots

https://bugzilla.gnome.org/show_bug.cgi?id=735455
3.14.0
gtk2: integrate improvements from atw1990@gmail.com

Improvements all around, especially in entries and spinbuttons.

https://bugzilla.gnome.org/show_bug.cgi?id=735825
update checkbox/radio design slightly
add SVG source for the gtk2 sized radios and checks