Added wider support to rich text formatting. The node label is now
taking advantage of that rich text formatting and also allows for html
input.

Also fixed a bug where the viewer 1 2 3… shortcuts wouldn't work.

Also fixed a bug in the restore default pref.
Merge branch 'workshop' of https://github.com/MrKepzie/Natron into workshop

Conflicts:
	Gui/KnobGui.cpp