Rework all icons into the iconfactory

Icons require absolute paths, so sonata/ui/icons.glade gets read into a
string, the absolute path added to icons, and then the string builds
an icon factory.

Removed unused icons. Made icon naming consistent.
Simplified and homogenized use of icons in Sonata

Merge remote-tracking branch 'others/hobophobe/iconfactory-from-string2'

Conflicts:
	sonata/library.py