Expander for the Quadra Module adds VC of AD, EOC and Analog OR

• 4 x EOC (end of cycle) pulse outputs corresponding to the 4 function generators
• Voltage control of attack and decay (with attenuators) of all four envelopes
• 2 x analog OR (aka peak circuit) logic outputs that are normalled to the two pairs of envelopes (1+2 and 3+4) with attenuators
• Special quadrature modes for envelopes 1+2 and 3+4 with jumper on pcb to select two different kinds of looping responses
• Skiff friendly depth