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.
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