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


Looks like you didn't pick up https://github.com/scala/scala/commit/17a1abbff6816d0693bb98869cd26c25f695cffa.

It would be really helpful to record the SHA of scala/scala from which you ported this, so that in the future merging is possible. It would also be great to discuss if this is a straight port, if if you had to make any interesting changes to fit into dotc.