Cleaning for collections. Persistant database collection.

- Added `destroy` method and event to Collection and QueryCollection
which will unbind all listeners on itself and children
- `createCollection` now renamed to `extendCollection` as we now create
collections and blocks within the constructor, and just extend them on
each load, extending now support destroying old collections - this
allows us to persist the same database collection
Merged master into dev-cleancollections
v6.25.0. Improvement.

- v6.25.0 March 10, 2013
	- Database is now persistant
	- We now destroy unused collections