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
Merge pull request #814 from huitseeker/793-reissue

Remove aspect hover
Introducing Utils API

It opens APIs to

 Utils
 DisplayThread,
 EclipseUtils,
 EditorUtils,
 FileUtils,
 OSGiUtils,
 ScalaWordFinder,
 SWTUtils
Documents the Utils API
Renaming [Pp]imped(\w+) to Rich\1
Switches to toplevel objects with public/private members