Make the sidebar dynamic depending on the user's rights This is done by doing the usual access checks that are also called when the user actually visits the page.

Have the sidebar be rebuilt on every request with callbacks This makes is possible for the sidebar constructing to take into account the current users privilidges etc.

Adds and uses a modified_by property in models/work.py This property is used to display the user who last edited the work in the document viewer. Fixes author being set on every edit. Also edited the style-sheet to fix issue i128. Patch by: Lennard de Rijk