and reworked persistence classes to through exceptions rather to fail silently
This fixes issue 2.7 of https://defuse.ca/audits/zerobin.htm, and thus (with commit a24212afda90ca3e4b4ff5ce30d2012709b58a28) also issue 2.8. (cherry picked from commit 0b4db7ece313dd268e51fc47a0293a649927558a) Conflicts: index.php
cleaned up CSS, changed template to output clean XHTML 5, added unit tests for 60% of the code, found a few bugs by doing that and fixed them
