Change problematic forms to use POST instead of GET

[Nicklas Nordborg]

Problematic forms are forms were the generated GET url get's too long for the web server. This usually results in an server response similar to:

Request-URI Too Large
The requested URL's length exceeds the capasity limit for this server.
Apache/2.2.8 (Unix) mod_jk/1.2.26 Server at base2.thep.lu.se Port 80

This ticket is related to #896 and #1032. Please add comments to this ticket with more information about "problematic forms".