Restore the WKT parser, example & tests

This is a first attempt to restore the WKT parser.
It is probably preferred to rewrite the parser to the `ol.format` namespace as well,
but I would first like to have some confirmation on this before doing so.
Now that `ol.View2D` [is gone](https://github.com/openlayers/ol3/commit/fa5f99c71655f7cdf61c2a541fe3334aeb3d4188), you'll want to change this to `ol.View`.