Chubgraphs and ChuGens don't support stereo operation

[heuermh]

From an email thread:

Chubgraphs (and ChuGens) don't support stereo operation at this time. Its something we've thought a lot about, but wanted to focus on getting mono operation right before venturing into stereo/multichannel. Thanks for bringing this issue up though.

For what its worth Chugins do support arbitrary numbers of I/O channels, but of course requires implementation in C++.

Added as an issue here for tracking purposes.