Sortable fixes. Double save prevention

IE10 filter fix, Sortable/MPTT fix

Print CSS. Mac/Safari shadow fix. Menu parser improved. Request argum…

…ent for list attributes

Django-Import-Export support. CSS fixes

List row and cell attributes

Django-CMS, Django-Filer support

Form tabs, form includes, new menu config and features

wysiwyg, django-reversion, fieldsets refactoring

Py3.x stability, Travis CI, Tests finished

Support for Django 1.4.0 restored (was 1.4.2)