b=999376 use integers to clamp maximum position in WaveShaper curve r=ehsan

float did not necessarily have enough precision.

Includes a -1 fix in the multiplier of the input signal to have
"a signal level of zero corresponding to the center value of the curve array".

--HG--
extra : transplant_source : %05v%A2%0A%CA%96%96%A7%B0z%AA%A7%02L%8Fm%B4TB%95
b=990841 work around bug 916387

--HG--
extra : transplant_source : %E5k%B8%F1%EC%A9X%EEj%C0DV%EAL%CE%3C%CB%8ERW