PEP 8 cleanups
Triggers and SQL beautified
Avoid duplicated actions in the triggers
extracting 'denorm_always_skip 'should be done later as othermodel could be a string at the time
Let the user decide what keyword arguments are passed to the denormalized field (no magic involved)
Denorm function could return either an object or a PK

Without this, foreign key fields (like 'some_id') could end up
having objects instead of IDs.
self-referencing foreign keys without a defined type for DependOnRelated fallback to forward
Not all Primary Keys are called 'id'
Multi-table support for denorm dependencies
Django v1.6: full django-denorm compatibility
Using quote_name for all field names.

Some fields need this (particularly those with lower and upper case
or those that otherwise would be reserved keywords).

Along the way, connection's using 'using' was normalized to be
consistently used and passed around where it was needed.
DirtyInstance model has unique together (content_type, object_id)
Added support for swapped models
Full compatibility with Django 1.6 (tests passing)