* Support link and group objects
* Support view sync by implementing view provider API getMDIView()
* Use handleChangedPropertyType() for object migration instead of
reimplementing Restore() because of a lots of changes in
PropertyContainer::Restore().
* Various other small fixes.
When clicking on balloon command, cursor is changing to balloon cursor.
It means user is ready to place a balloon (anywhere on the page).
Balloon object is not created until user click somewhere.
Balloon command can be aborted pressing escape or when page view lost
focus (in other words, when user clic somewhere else than the page).
+ some are doxy others are just comment code.
+ some minor whitespace and grammatical tweaks.
+ app/SCL/* typos have also been submitted upstream (https://github.com/stepcode/stepcode/pull/366). So it's ok to merge them in to master.
