Update to gnome-control-center 3.6 git as of today

Most significant change is bigger sizes for the window and all icons. This is
a candidate for a version update but no bump is yet applied.

* configure.in.in: now requires x11
* src/cut-n-paste/: update code from gnome-control-center
* src/{control-center.c,gnome-control-center.c,shell.ui}: rebase on updated code
* src/patch/: update patch to current changes
Remove broken gmenu, show maximized window decor
Use smaller margins around panels

This makes the default screen look significantly better (the bottom row of
icons is no longer cut off).
Bump version to 2.21.4
Merge pull request #1 from Catanzaro/master

Update for gnome control center 3.6, bnc#803195