Export and externalize Control.setMap
Create ol.inherits alias, and export it
Add a custom controls example

Inspired from @cedricmoullet's ZoomExtent example in https://github.com/cedricmoullet/ol3/commit/3312c37ed0ac93e9b3c2cb0cea76a070ea1c2cf4.
Export Control.getMap
Externalize Control.handleMapPostrender