Improve audiomuxer to be more user friendly.
Improve audiomuxer to be more user friendly.

Check options and inputs more strictly and report if incompatible.

maki-rxrz/L-SMASH,canbal/l-smash,dwbuiten/l-smash,silverfilain/L-SMASH,mstorsjo/l-smash,silverfilain/L-SMASH,silverfilain/L-SMASH,maki-rxrz/L-SMASH,l-smash/l-smash,l-smash/l-smash,l-smash/l-smash,dwbuiten/l-smash,mstorsjo/l-smash,canbal/l-smash