Markup for lesson 7
Merge branch 'feature/learningwebgl' of github.com:Asakeron/cljs-webgl into feature/learningwebgl

* 'feature/learningwebgl' of github.com:Asakeron/cljs-webgl:
  Updated examples to match new texture API.
  Parameterized texture-unit in set-texture in cljs-webgl.buffers.
  Moved load-image and load-texture to learningwebgl.common.
  Most options are parameterized in create-texture.
  Merged texture-min-filter and texture-mag-filter into texture-filter.
Allow multiple simultaneous key press events
unpack-flip-y-webgl --> true
Learning WebGL, Lesson 7 - implemented