Fix argument parsing

[marioortizmanero]

This should close #63

[Aerion]

Thanks for the swift response.

The original command is now fixed, but it seems to have introduced a regression:

# No errors expected
$ ./pulseaudio-control.bash --osd --icons-volume "A"
Unrecognised action: A

# This works great though!
./pulseaudio-control.bash --osd output
64% Sink #89

[marioortizmanero]

Ah, whoops. Looks like shift modifies the function's arguments instead of the global arguments. Not the prettiest, but it should be fixed now.

[Aerion]

Sweet, looks good!