Also removed the negbandpass & neghighpass parameters
and replaced them with bandpass & highpass set to -1, to
fit the switches better to the GUI.
Closes#51, closes#173
Using polyphony 2 gave errors: 16 instruments with polyphony 2 + 1 global was a total of 33 voices and gave errors when sointu compiling. User will set anyway polyphony as needed for every instrument, like 1 for most instruments, so just use NumVoices 1 always.
