Merge pull request #18 from tagawa/music2

Added margin setting for timing
Merge pull request #19 from tagawa/music2

Added support for time lag
Tidied up code for sound elements
Merge pull request #20 from tagawa/optimisation

Tidied up code for sound elements
add self inst and key var
Merge pull request #22 from HTML5ExpertsHackathon/setMute

add self inst and key var
set mute inst for player
Merge pull request #23 from HTML5ExpertsHackathon/setMute

set mute inst for player
Added triggers for good hits