Some removal of old code.
Added a open/close button to the side pane.
Fixed the functionality and look of the open/close side pane
more refinements of the sidebar.
Added "Goto Target Set Button" on the library options side pane.
cleanup of the sidepanes of the library options, problem set list, user list.
Revert "Added "Goto Target Set Button" on the library options side pane."

This reverts commit 1fb814feb35fffe6bf8feae29d99a3a3e30ae281.
cleanup of the sidepanes of the library options, problem set list, user list.
Fixed some errors with message templating.
Added logout functionality
Added stop acting as user functionality.
More cleanup of messaging in Library Browser.
Merge branch 'ww3' of https://github.com/openwebwork/webwork2 into ww3-feature/clean-up
Only certain side panes can be viewed for each main view.
Fixed some issues with the stop acting as user.
Changed sidebar to side pane to be consistent.
Changed sidebar to sidepane.
Fixed link to ww2 in order to keep effective user.
Changed sidebar to sidepane.
Changed the way "act as user" works in the class list view.