[NixIO] Handle channel names like other obj names
[NixIO] Handle channel names like other obj names

Neo channel name is stored in the Source metadata and restored on read.

rgerkin/python-neo,NeuralEnsemble/python-neo,mgr0dzicki/python-neo,INM-6/python-neo,JuliaSprenger/python-neo,apdavison/python-neo,theunissenlab/python-neo,samuelgarcia/python-neo