just moved all the audio stuff into its own files. Created a structure
for storing configuration data in... the intent is that it will be
stored to EEPROM (using EEPROMAnything). It does compile now, but
haven't actually tried it out. Notable learning points: need to set
micGain AFTER selecting the mic input. So lot of code now to take care
of trying to smoothly mute and unmute things.
