Update to code as per suggestions on PR and IRC.
Update to code as per suggestions on PR and IRC.

The code has been changed following peer review.
*Both the map and build instructions have been abstracted out of the module.
*Functionality has been expanded to include multiple passes allowing custom exit creation.
*Documentation expanded and a further example provided.
feend78/evennia,titeuf87/evennia,jamesbeebop/evennia,titeuf87/evennia,feend78/evennia,titeuf87/evennia,feend78/evennia,jamesbeebop/evennia,jamesbeebop/evennia,feend78/evennia,titeuf87/evennia