TextGeometry; creation and implementation

[ruby0x1]

Current text rendering is efficient in that it creates as few geometry as needed (by texture page break for batching) but it's inefficient in that it creates a new geometry each time the text is re-drawn. This was older placeholder implementation so a text specific Geometry class is needed.

Needs:

• aware of per-geometry vert count limits
• avoid if possible creating trees of transforms and use the parent transform
• dynamic text updates reusing pool of vertices for letters
• flush excess letters from pool for when you know you wont need the excess
• ensure geometry transform / origin is not limited by position/align/bounding
• be future proof for per letter/word etc styling
• be future proof for rendering easily to a image buffer for effects etc
• be future proof for SDF shaders and other flexibility

[ruby0x1]

This is completed in a local branch, once I have tested more thoroughly against larger projects (so far 2 large projects have had no major side effects of all the changes) it will migrate to master.