Revert "coalesce texture uploads at the beginning of a frame"

This reverts commit 8c2c7f769fffcd217698824719b0a0ba45fbef13.

See #454

Conflicts:
	src/geometry/glyph_atlas.cpp
	src/geometry/sprite_atlas.cpp
linepattern in progress
Make renderLine more similar to JS
Add SpriteAtlas::getPosition()