Initial commit

First draft of a design. We use the theme from the website, but adapt it to fit a smartphone. Moreover the tag layout is already in use, together with MathJax + XyJax and the part of the HTML of an input form.
Finished the first draft of the layout
Improved form layout and added tag CAPTCHA
Implement form field saving
A shorter version of the CAPTCHA text
Improve HTML5ness of the form
Started the PHP code

This is just a placeholder actually
Removed the site field

I guess this is just wasted input here
Implemented existing slogans
Message regarding hidden slogans now contains link
Slogan input shouldn’t depend on size
I like a text area for the slogan better
Probably this number is better for smartphones

As 480px seems to be a common number for the horizontal resolution. But probably we want to increase the page’s width, if more space is available, or something.
Implemented API call to get a random tag
Requesting new tags is done by `input.php`

We just send the user to the file `input.php`, which will request a random tag.
Massive restructuring

I should’ve been stricter with my commits:
* we can now display errors
* random tag versus specific tag
* handle required fields using JS (to make the skip button work without the user having to fill in things...)
Changed the workings of random tags

Calling `input.php` without a tag turns the code into a redirect to `input.php` *with* a tag that was suggested by the API.
Give more information regarding slogan input
Information on chapter and section

This probably needs some checking, but I guess the relevant tags never occur directly under a chapter?
Fixes #5