Various frontend improvements

Optimise shadow image, fix chmod in README, HTML5 doctype, make all JS
external, concat+minify JS
More frontend tidying

Add “tick all” and “clear” buttons to course list, setting height of
course list so it becomes a scrollable area with “submit” button is
always visible at the bottom (looks better when you show all courses
for a year)
Merge branch 'master' of github.com:Pezmc/CS-Timetable-to-iCal into rd3k-master