Remove google.exports

This .exports file made goog.require be exported as a null function. This was needed to be able to run the ol3 examples uncompiled against the ol.js build. Now that host-examples target removes the goog.require statements from the examples' js files (74b8fea6) we don't need to export goog.require anymore.
Fix typo in View2D:getExtent
Merge pull request #705 from elemoine/getextent

Fix typo in View2D:getExtent
Merge pull request #701 from elemoine/rm-google-exports

Remove google.exports
Use latest gjslint version (2.3.10)
New gslint doesn't like va_filters
Merge pull request #707 from elemoine/gjslint

Use new gjslint version (2.3.10)
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