Revision 640242

Cleanup and minor refactoring:
* consolidate addId() in AbstractLayoutManager
* replace getPSLM().addIdToPage(getXXX().getId()) in various LMs

Smaller changes/cleanup in the affected LMs include:
* removal of some redundant casts
* simplified conditionals
* avoid duplicating the reference to the FObj as much as possible:
  the reference is already stored in AbstractLM, yet every subclass seems to
  add another reference...