On reset, deselect all user labels, except owner label
Created "obsolete" package and moved classes into it

These classes may still have useful information in them, so I don't
want to delete them.
Change helper method from addLabels to addSelectedLabels

The name "addLabels" is too close to DataTransfer#addLabel.
If a label is altered*, mark model as unsaved

*Altered = added, deleted, or selection state changes.
Fix logic error in Perspective#reset

I incorrectly used ! in an expression.
Use constant instead of string literal in DataTransfer

An oversight.
Add helper method DataManager#updateModelSaveState

Combines calls to two methods that are often used together.