Smart regions, bug fixes, a4j argument parsing and database schema versioning.

Improvements to the region system including

• Region hierarchy tree (inheritance, priority for overlapping regions, etc.)
• Region snapshotting/versioning (including delta files for subsequent snapshots, scheduled resets, etc.)
• Simple but powerful control about which events get cancelled and when

Skipping 5.1.0 and going straight to 5.2.0