Rename the _feincms_content_model class to prevent name clashes

Fixes #399.
Fix test_36_sitemaps
FeinCMS v1.7.2
Fix ckeditor init template. While there, fix trailing commas in javascript arrays, IE absolutely hates them.

Contributed in #389 by Hedde.
Take a stab at fixing #395

Before, moves to the right of an existing node were handled as moves
to the left.
Take a stab at fixing #395

Before, moves to the right of an existing node were handled as moves
to the left.
FeinCMS v1.6.5
FeinCMS v1.7.3
FeinCMS v1.6.6

The tarball-was-broken release.
FeinCMS v1.7.4

The tarball-was-broken release.
Look, it's 2013

Thanks, Marc Tamlyn.

Refs 493e2ea62c9ee24b8440cc029d7a9c7d94d6e9f9.
Merge remote-tracking branch 'official/master'

* official/master:
  FeinCMS v1.6.6
ct_tracker: Do not call invalidate_cache if the base model does not have it
Check that short_title is really callable
fix medialibrary admin to work with new extension mechanism
add documentation for extension mechanism and mediafile admin widgets
allow other extension after datepublisher to use add_extension_options()
Changed '&' to '?' in youtube URL
Updated models.py -> invalidate_cache()

A problem occurs when using best_match_for_path() if the desired path does not already exist at creation time.  On first run, best_match_for_path() will populate the cache with the best possible match.  When the user creates the actual desired path however, the cache is never updated as the code only flushes _original_cached_url (which is empty for a new page).

This is resolved by *also* flushing _cached_url at the same time.
Merge pull request #416 from rantecki/patch-1

Changed '&' to '?' in youtube URL