Unify "(items|albums|photos|movies)/show" to "items/show".
- the three views are still made the same way, but triplicated(!) code is gone.
- "items/show/<id>" finds the item and does a 301 redirect to the canonical URL.
- bootstrap routing is much cleaner.
Unify "(albums|photos|movies)/edit" to "items/edit".
- removed a *ton* of triplicated code.
- put all edit-related i18n strings in one place (nice for standardization!).
- removed Controller_Photos and Controller_Movies completely.
Add some comments for each function in Controller_Items.
Move Controller_Albums::get_display_context() to Controller_Items.
Move "albums/add" to "items/add".
Move Controller_Albums::get_siblings() to Controller_Items.
No more separate (and largely duplicated) Movies/Photos/Albums controllers!
Merge pull request #349 from shadlaws/fixes_20130504_part3

Fixes 20130504 part3