Enomalism developer guide

I've started work on the Enomalism developer guide. I've only just begun writing it so there is a lack of content at the moment. However, the good news is that I'll be frequently updating it. So check back often.

The guide hopefully be a useful starting point for creating Enomalism extension modules as well as using the exposed API. If there is any area that is lacking (that doesn't already have a TODO label) or missing completely, be sure to let me know.