Use Plovr 2013-rc3

Finally, there's [a new release of Plovr](https://groups.google.com/forum/?fromgroups=#!topic/plovr/Pk_NXY1-zl8) that includes a more recent version of the Closure Compiler and the Closure Library.

This PR updates ol3 to use these updated versions and includes a number of fixes for errors detected by the improved compiler.

Note that the more recent version of the Closure Library means that the unused `goog.require` detection code to exceed [an arbitrary limit in Python's regular expression code](http://stackoverflow.com/questions/478458). You'll need to `pip install regex`.