Update Hodgkin-Huxley example to follow Rodolphe Sepluchre papers

[Richard Murray]

Rodolphe has written a number of papers on Hodgkin-Huxley from a controls perspective and we should read through them and update our examples appropriately. Papers attached.

[Richard Murray]

Another reference: book chapter from Rodolphe that is relevant.

[Richard Murray]

Issue #13 was marked as a duplicate of this issue.

[Richard Murray]

Exercise 5.23 should be updated to follow whatever changes get made to respond to this issue.

[[e-mail]]

Richard, Rodolphe wanted to have a different reference, i have added the ref in ambook.bib and I changed the reference in the text, have also committed the changes.

[Richard Murray]

Thanks, Karl. Is this the only change that we needed to make? My sense was that you were suggesting that we change the example to match more of the style (notation?) of Rodolphe's work. But if all we need to change is the reference then that is great (and I will close out this issue).

[Richard Murray]

Karl: take a look also at issue #21, which is about making Exercise 5.23 (spike generation in neurons) be consistent with Rodolphe's work.

[Richard Murray]

Issue #41 was marked as a duplicate of this issue.

[Richard Murray]

Fixed in commits 733a92c, 45ce32e, and 3e5bead.