Begin adding text support
Text rendering works
Legend works
Factor out FPS limit
Add legend interface
Add module to cabal file
Merge branch 'master' into data-flow

Conflicts:
	Graphics/Rendering/GLPlot.hs
	Graphics/Rendering/GLPlot/Types.hs
	Test.hs
	gl-plot.cabal
Rework event model
Simplify data flow
Simplify context management
Fix haddock
Improve Haddocks