Update gh-pages
Enable music and disable cache
Prefixfree Dynamic DOM plugin added
Fix ending screen
text fix
Font change
Add reset option
Update core.js

Adding audio functions that can be usefull in the future
Add 2 forest backgrounds
Bug fix for the help of the chronology engine. Now the two first bubbles show the right answer.
Bug fixes for the associate engine :
First : using help while answers to vanish are in boxes used to disable these boxes forever.
Second : switching an answer from a box to another used to disable the first one forever.
Complete doc on engine creation
Refactoring chronology engine
Fix episode Ending Screen
Fix 404 resources