Added date checking on critiques + bug fixes

The home page of a student now filters critiques by date, if the
submission date hasn't passed then they won't appear even if assigned.
Fixed up bugs in _edit.php for admins
comment system css and js changes.

Fileselect css/js pending.
Added Botdetection to signupAdmin + signupAdmin auth's correctly
Minor visual updates to admin forms

edited create.php , edited critique.php  , edited main.less, removed
commented out lines in main.less
Dismissible alerts

Create, Critiques and Edit now have alerts. Needs JS to hide these
alerts when pages initialise.
Redesign to edit and studentReview
Optional Gif to replace plain login background.

To test, comment out background color and uncomment background: url
etc..
We could make this an unlockable perk?
Quick fix for alert on critique.php

added link to bootstrap.js
main.less changes
minor site changes

Updated student home widgets. Updated create assessment page (merged
semester into the course selection). Updated some error messages in
assign critiques
more css changes.
Added time checking to create and edit assessment

Now checks if the entered string is valid 24 hour time.
codecritique changed with new fileselect
prettify is fixed! hooray!
fixed more stuff
Updated sidebar Review links

Can now access critiques via the sidebar
changes to hrefs and header(location:) urls

removed '../' and '/' from all links to hopefully stop the object not
found errors
Background change, fix your shit.
New Signup page
Small fix for text colour on background.

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