Added annyang.removeCallback(), Speech KITT and a bug fix

[Added] - annyang.removeCallback()

New method allows removing callbacks you attached to events.
Check out the annyang.removeCallback() documentation for details and sample code.

Announcing Speech KITT

Meet Speech KITT - a new library that makes it as easy as possible to create a GUI for users to interact with Speech Recognition

[Fix] Bug

Fixed a bug which caused an error to be thrown when a command that was called by annyang included calls to to remove commands.

Test Coverage Improved

Improved test coverage of annyang using the new Speech Recognition mock object - Corti.

Awesome people ⭐

A lot of new contributors have helped make this version possible!
Special thanks to:
@soney - Found and fixed a bug when removing commands from command
@qgustavor - Documentation
@siawyoung - Added new tests and helped new contributors
@Endi1 - Added new tests
@evaldosantos - Added new tests
@theotow - Added new tests
@mdboop - Added new tests
@wizardsambolton + @MartinKoutny - Idea for removeCallback() method