Update README: don't need group_concat any longer
Prepare null value for database operation

Apparently, things do not work as one would hope they do.
Let problem and solution forms be generated by class

This required restructuring them a little bit, unfortunately.
Don't print proposers as links in TeX
Replaced &_uml; with UTF-8 umlauts
Escape proposer names properly

Proposer names with apostrophes didn't work in single-quoted attribute
for datalist object.
Moved index script into pages directory

After all, it's just a page. And it's for browsing through the database,
not necessarily the starting page.
Moved icon to image directory