Add sprite and spritebatch classes. Add utils to covert pixel coord to ndc.
implement sprite batching and drawing
texture::region accepts w < 0 and h < 0 to use full texture width or height
Fix error skipping batching vertices
implemented creating spritesheet
docs
Merge branch 'add-spritesheet' into api-2d
Merge branch 'api-2d' into develop
removed picking api
Merge branch 'remove-picking' into develop
moved triangle and line struct into geometry
move sprite.cpp to src
removed from repo
start shader in begin call so uniforms can be set outside of spritebatch
added quad structure to sprite that is updated only as needed by the spritebatch
fixed warnings in camera
fix errors in entity and framebuffer
fix truncate warnings
fixed sprite warnings
fixed spritebatch warnings