Javaparser

Java parser for dotty.

As we discussed, three tests are still failing:
* t2409:
  Requires import of companion object before first constructor.
* t1751 and t294:
  Tree transformer does not transform repeated method arguments within an annotation instantiation.

Review by @odersky @DarkDimius


I ported from https://github.com/scala/scala/commit/9753f23f9362b25a9f481b11dd8d51187187882a, which was before https://github.com/scala/scala/commit/17a1abbff6816d0693bb98869cd26c25f695cffa.

I have updated the first commit message with the SHA and some discussion of the changes from scalac. Only very minor changes were needed.