Font support

[henry-brisson]

• https://threejs.org/docs/#manual/en/introduction/Creating-text
• https://github.com/Jam3/three-bmfont-text
• http://www.angelcode.com/products/bmfont/

[henry-brisson]

This was partially implemented in #11.

The full implementation still includes text that can be rendered as a sprite, for HUDs and stuff.