AI 143157: am: CL 142852 ADT fix #1682502: New XML File Wizard root combo is sometime...

AI 143157: am: CL 142852 ADT fix #1682502: New XML File Wizard root combo is sometimes empty.
  Two issues in fact:
  1- On some selections the resource type is determined before the
  root values are computed.
  2- Added an sdk target change listener to refresh the project's roots
  if the SDK was still loading or if the project changed targets.
  The New Project Wizard has been updated with a similar sdk change
  listener to refresh the target selector. This is useful when the NPW
  is used before the targets have finished loading, e.g. upon lauching
  Eclipse.
  Note: this requires CL 142690 to compile.
  Original author: raphael
  Merged from: //branches/cupcake/...

Automated import of CL 143157