RAII or other better memory management for rxd grids

[ramcdougal]

The word free appears 109 times in src/nrnpython/grids.cpp.

Nevermind that that's C-style not C++-style, but surely we can do better memory management.

[D-McDougall]

That file holds the RxD data in a linked list :(

Do you think that neuron's new data-container system would be a good fit for holding this data?

[ramcdougal]

In fairness, it's a linked list of grids (e.g., calcium in the cytosol across the entire model could be one entry)...