MDL-18229 gradebook: Initial commit of LSUs Quick Edit Plugin

Renamed to Single View in MDL-47289.
MDL-18229 gradebook: Added filter icons for activities and users.

Corrected CSS for grades column, was far too large.
MDL-18229 gradebook: Single view navigation corrected.

Usernames link to user profiles.
Activities to their activity page.
Merge branch 'MDL-18229-master' of git://github.com/zbdd/moodle into MDL-18229-master
MDL-47347 added basic navigation to top and bottom of gradereport_singleview
Merge branch 'MDL-18229-master' of github.com:nebgor/moodle into MDL-18229-2-master