Getter and setter support for bindTo
Add tests for ol.Object#bindTo getters and setters
Remove 'valueAsNumber' property from ol.dom.Input

Use bindTo.transform functions instead
Notify target object after transform functions change
Merge pull request #1198 from fredj/bindTo_transform

ol.Object#bindTo: getter and setter
Remove '(Optional)' from Description
Proj4js no longer needed for wmts-from-capabilities example

The WMTS capabilities document of the Vienna map has changed. It
no longer defines a tileset for EPSG:31256, so it can be parsed
without having Proj4js and a projection definition for
EPSG:31256.
Merge pull request #1280 from ahocevar/wmts-vienna

Proj4js no longer needed for wmts-from-capabilities example
Merge pull request #1278 from fredj/apidoc_optional

Remove '(Optional)' from Description
Default projection does not need to be provided

The wmts-from-capabilities example should focus on creating a
WMTS source from capabilities, so it should not distract by
configuring a projection that does not need to be configured.
Merge pull request #1281 from ahocevar/simplify-wmts-from-capabilities

Default projection does not need to be provided
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