Disabled picker buttons only grey out their contents
Generally prettier CSS
Added image size
Merge branch 'master' into image_size

Conflicts:
	src/core/LiterallyCanvas.coffee
	src/core/util.coffee
Fixed crash when imageSize isn't present
Updated getBoundingRect calls to be more sane
Slightly better brush size picker
Every shape gets a GUID
LinePath and ErasedLinePath store data much more efficiently
saveShape() can save shapes below other shapes, and avoid triggering the event
shapeSave event includes afterShapeId
afterShapeId -> previousShapeId
Eraser doesn't crash
Merge pull request #159 from irskep/shape-ids

Shapes have unique IDs; [Erased]LinePath stores data more efficiently
Visual tweaks
Fix stroke width selection styles
Merge pull request #184 from irskep/css

Nicer button styles, brush size picker
Handle imageBounds option a little more cleanly
Fixed centering when canvas is resized
Merge pull request #181 from campaul/image_size

Added image size