Use the new copy/cut/paste fallback icons from avogadroapp.

Change-Id: If528a36227329355f6b740169df24ed98936012b
Add fallback icons to QtGui, add standardIcon function.

Change-Id: Idcd4068db698a255da0077e74887093f844f2846
Merge remote-tracking branch 'origin/master' into copy-paste-icons

Conflicts:
	avogadro/qtgui/CMakeLists.txt

Change-Id: I4b8f40a18e14d32283acc6b0e49df5614f874759
Merge topic 'copy-paste-icons' into master

c0aa1993 Merge remote-tracking branch 'origin/master' into copy-paste-icons
a0f15f8f Add fallback icons to QtGui, add standardIcon function.
f10ceab4 Use the new copy/cut/paste fallback icons from avogadroapp.