Alternative @SidedProxy setter for Scala.
Some more Scala @SidedProxy adjustments. Now properly supporting pure singletons, i.e.
object C {
  @SidedProxy(...)
  var proxy: P = null
}
Removed fallback, as all such singletons are properly handled by the new code now, and class implementations fall back to the code also used for plain Java mods.
Merge declaration and initialization of a variable.
Merge pull request #230 from fnuecke/master

Alternative setter logic for @SidedProxy in Scala classes/mods.