[patch] add 'not'-variants to some lookup kwargs

[hugo]

Currently there are no 'inotcontains', 'notcontains', 'notstartswith', 'notendswith' queries which makes it awkward if you want to build a query that searches for all stuff that includes 'foo' but doesn't include 'bar' - you need to fetch IDs and filter IDs based on those results yourself.

This could be done in two ways: either just add those query lookup kwargs to the backends (mapping them to the matching NOT LIKE clauses) or enhance the AND/OR combinator syntax by introducing not handling (creating a Qnot object that will render as NOT(condition) in the SQL). The first version is much easier to do and fit's nicely into the current kwarg-based query syntax, so I would opt for that version.

[hugo]

add notcontains and friends

[hugo]

accidentely fixed in [1534]

[hugo]

reverted changes in SVN and reopened ticket

[Jacob]

(In [2422]) Added QuerySet.exclude() which does the opposite of QuerySet.filter(). As a side effect, the "ne" lookup type no longer exists. This fixes #966.