Only set interacting hint when modifying the view
Merge pull request #1277 from tschaub/interation-hint

The ol.interaction.Drag subclasses set interacting hint as needed.
Factor out ol.webgl.Context
Track current program in context, rather than renderers
Rename ol.renderer.Layer#renderFrame to prepareFrame
Add and use ol.renderer.webgl.Layer#composeFrame
Factor out layersToDraw
Add and use ol.renderer.canvas.Layer#composeFrame
Experimental canvas vector layer renderer
Use experimental canvas vector layer renderer
Add synthetic-data example
Pass context instead of canvas when creating ol.renderer.canvas.Vector
Render vector features directly to output canvas
Render features even while animating and interacting
Remove stray call to composeFrame, thanks @elemoine
Remove unused vector layer canvas
Correct transform and remove unused variables
Add ol.Color.parse
Add initial canvas-like API
Add ol.replay.transformPath