PRD-4443: Fixing invalid event handling for query-attribute changes.

Also: Refactored report-tree to split it into a layout-tree and a data-tree. The class was trying to be both kinds, which is bad design. Duplicate code is now in AbstractReportTree.
PRD-3343: Event handling for adding or removing parameter or expressions made more specific. This allows the JTree to preserve its selections and state.
[CM-219] Update javassist to 3.12.1.GA
PRD-3343: Adding better support for sub-report parameter changes so that the data-tree can handle them more targeted.
Merge pull request #31 from tmorgner/PRD-4443

PRD-4443 and PRD-3343 - Fixes to the even handling on data-tree
PRD-4445: Fixed an NPE in the drag-and-drop handling when dropping onto an empty report. Also fixed precision issues where dropping an element onto an empty root-band placed the elements on a different location than the drop position indicated by the mouse.

Code smell: Refactored drag-and-drop handling and condensed duplicate code.
Merge pull request #32 from tmorgner/master

PRD-4445 - fixed bordercase crash introduced earlier in PRD-4313