More icon work by Michael Growberg:

More icon work by Michael Growberg:

Major changes since last version:
*all icons are done
*changed look of raise/lower icons
*"tweak" tool uses "smudge" icon from art libre set
*transform icons taken from art libre set
*align icons taken from art libre set (or extrapolated from their style)

problems:
ink pressure/tilt settings don't show (but the old ones do for some reason)
some icons are taken from the desktop's icon theme and so the layer icons should
match the ones in the layer dialog but don't match on all platforms
same goes for paste icons like paste in place that don't always match the look
of the generic paste icon.