WebFrontend: Complete schedule editor (Beta)

There is still some missing functionality and it's only been lightly
tested. Search/Custom rule editing hasn't been tested at all.

Use entirely at your own risk. Feedback would be appreciated.

Refs #11938
Scripting: Add support for php style form arrays (name='foo[a]'). See http://www.php.net/manual/en/faq.html.php#faq.html.arrays