Create functionality for supermodules, that can combine multiple modules and be used as a module itself in the vessel_array.csv

[FinbarArgus]

For example. We should be able to have modules for each ion channel, then create a super-module for the soma, which couples the ion channel models. Then the soma super-module couple be coupled with axon models etc. in vessel_array.csv without having to specify each sub-module.

The heart could also be a super-module made up of sub-modules for each ventricle and the valves.