RFE: rename outgoing channel in Math and Shuffle CHOPs

Often the Math and Shuffle CHOPs will get many channels and combine them down to one with some operation. It would be nice if we could, in the “Common” tab or something, choose new channel name(s) based on what that OP just did, rather than just the first channel’s name plus a 1, especially if the new data is not represented well by either of the original channels’ names. Similar to functionality Select CHOP has.