color_mix: Added missing translation request in color
[l10n] Updated Italian translation.

Luca got no request from the Italian translation team.
This file seems complete so I commit it.
Hangman game improvements
- Support for Multigraphs
- Support for optional separate wordlist
po files need to be updated
Independent wordlist for reading activities. Creating an extra wordlist is optional.
Read number of levels from XML file. Improved colours.
Levels optimized for typing game
minor fix to avoid an error message if there is no equiv list.
lang-activity: better exercise, overall improvements.