Add print CSS

[abradbury]

Initially focus on the event pages, as people are most likely to print these pages

• Remove whitespace from header image location
• Remove breadcrumbs
• Print URL of all links in brackets after the links (and fully-qualify)
• Remove footer entirely (though maybe leave copyright?)
• Remove venue side-bar, or place at bottom of event details, so event details span full page
• Make tables more defined i.e. header row