Splits out vsBuiltInFont into its own source file.
Adds vsFontRenderer.

Has a much, MUCH simpler interface to building font geometry.

Next step will be to remove all the old font geometry building
interfaces from vsFont, as they're inconsistent in how they operate.
Removes all font rendering functionality from vsFont.

vsFont now solely builds and stores the necessary data which is then
used by the vsFontRenderer to create renderable geometry.

This gets rid of a *lot* of crufty, buggy, and highly duplicated old
code.