Mnemosyne 2.3.3 released

[Peter Bienstman]

http://mnemosyne-proj.org/download-mnemosyne.php

Mnemosyne 2.3.3 : 2015-04-13

(Note that for Windows users we recommend uninstalling the previous version
before installing the new one.)

-Fix regression where it was not possible to grade map cards (reported by 
 Mateusz Konieczny).
-Also allow mass conversion of cards to Cloze and Sentence card types 
 (requested by Chris Nadt). 
-Change ',' to ' - ' when importing legacy tag names (reported by Matthias 
 Ernst).
-Fix some keyboard shortcuts while displaying map cards (reported by 
 Mateusz Konieczny).