Remove libtess.js
Add tests for ol.coordinate.add().
Add tests for ol.coordinate.createStringXY().
Add tests for ol.coordinate.equals().
Merge pull request #2282 from marcjansen/coordinate-tests

Add more tests to ol.coordinate
Merge pull request #2281 from tschaub/remove-libtess

Remove libtess.js.
Depends on closure-util version 0.18.0
Fix the closure-library version

The version is the same as the one provided by plovr-81ed862.jar