Fix docComment asking forever in case of symbol not owned by a class
Remove persistence of PC doc comments.

Comments obtained by parsing are cleared at each typer run.

- fixes memory leak
- makes Scaladoc slower

It's possible (and easy) to reset those comments only at reconciliation,
but the test doesn't trigger reconciliation (it types all the time).
A more composed fix : clearing DocComments at each reconciliation

and Memory leaks test triggers reconciliation
Merge pull request #810 from huitseeker/hotfix/scaladoc-memoryleak

Control persistence of PC doc comments.
Merge pull request #813 from huitseeker/792-reissue

Fix ScalaWordFinder AIOOBE
Remove `HoverAspect` and `IScalaWordFinder`

I'm not entirely sure if the removal of `HoverAspect` doesn't break
anything. It is definitely not used in Scala hovers, because the Scala
IDE has its own implementations. It may be used by some Java hovers, but
I couldn't find one that actually uses it. In the worst case this change
means that some Scala elements are no longer shown in Java hovers.
Conflicts:
	org.scala-ide.sdt.core/src/org/scalaide/util/internal/ScalaWordFinder.scala