Determine Ion Channel Default Lists for Muscle Cells and Key Neurons

[slarson]

We should accumulate lists for muscle cells and key neurons of ion channels that we need to place into the muscle cell model and to use as defaults for the c302 model.

We made an early attempt to do this here: #31 -- we should look through the comments made there and extract what we learned. It seems like we didn't fully finish that time.

We should put the ideal neuron ion channels into this issue: openworm/CElegansNeuroML#34

We should put the ideal muscle cell ion channels into this issue: openworm/muscle_model#63

[VahidGh]

Some key ion channels for muscle cells and motorneurons are discussed under this issue.