Add on-demand font generation
Expand default font charset range from 128 to 256
Allow the color css property to change image color
color-multiplier property added to tiled decorators.
Add opacity property to control element opacity.

Opacity is a number from 0 to 1
Don't use a different font handle per charset

One handle can handle all the charsets.
Make FontFaceHandle and UnicodeRange outward facing classes
Implement fallback fonts for libRocket
Fix crash in libRocket by preventing access to unallocated memory
Update cmake paths