Comment 8 for bug 1233810

I'm about to submit a new version. It makes several changes:

 - The docstring for set_tmp_ecdh_by_curve_name is improved.

 - There are a lot more curve constants (I think I got all of them). I also expose the SN_ constants.

 - I added SSL.ELLIPTIC_CURVE_DESCRIPTIONS. This is loaded at startup from OpenSSL, so it will reflect the list of actual supported curves. On Fedora, it looks like this:

{415: u'X9.62/SECG curve over a 256 bit prime field',
 715: u'NIST/SECG curve over a 384 bit prime field'}

On Ubuntu, it's a huge list. I confirmed that I added the NID_ and SN_ constants for all of the Ubuntu-supported curves.