### Some updates resulting from using the library in production.

* The Angular executor now injects into the constructor **and/or** the execute method of a command object.
* Added an `unmap` to the `AngularCommandMap` to facilitate removing commands.
* Fixed some broken unmap logic in the `CommandCenter` to facilitate the above.
* Implemented `fireOnce` for mappings.
* Added a sprinkling of comments on API items.