Improve assessment grid input

Start again with post-backs only (add ajax again later).
Make auto-selection of input box more natural.
Separate surname from forenames

Explicitly separate name parts to ease integrations with external system.
Add total marks to an assessment

Remove max result from the grade boundaries.
Improve assessment tabbing order

Add explicit tab indexes to inputs to improve entering multiple marks at once.
More assessment editor tweaks

Add more tab indexes.
Separate surname and forenames columns.
Simplify and compress table styling.
Implement deleting an assessment
Style the create assessment view to look like the details view
Make all tables condensed