Logger

Implemented a new Logger class that manages debug output. Debug messages can be sent to either the Flash console or the Javascript console or both.

Replaced all existing trace with the new Logger.log function.

Updated Read me.
Hmm, one specify the log facility (i.e. `trace` is the function that outputs) and the other the language (`js`). 

Perhaps better keys would be 'trace' and 'console' ?