Added an initial hotkey utilities implementation.
Added hotkey mapping init code to the editor widget.
Updated the editor widget to use the new hotkey code.
Fixed undefined behavior in the editing component's constructor.
Cleaned up some overly long lines.
Added some structure which will be used to implement unit tests.
Fixed a small memory "leak" in the unit test superclass.
Added some additional test suite assertion functions.
Added tests for QomposeHotkey's various constructors.
Added tests for QomposeHotkey's copy, assignment, and compare functions.
Fixed QomposeHotkey's match function to work as intended.
Added tests for QomposeHotkey's match function.
Added tests for QomposeHotkeyMap.
Updated/fixed QomposeHotkeyMap and its associated tests.

The HotkeyMap now returns const pointers, since those are all that are
necessary, and it iterates over its values internally much more
efficiently.

Additionally, this fixes some various potential memory errors.