Explicit commit when updating tasks database tables
Add rollback method to database API
Minor fixes friendlier messages if mercurial repo / psp not available
Add fold/unfold all edit menu option
Fix grouping in select database API
Avoid using recent files for task-focused interface:

 * Open context files in relevance order
 * Store correct open/close status for context files
 * Do not overlap with FILES configuration section
Clean-up of database debug messages
Removed/cleaned-up debug message prints