Cleanup of the EC API

["Angus Robertson - Magenta Systems Ltd" <angus@xxxxxxxxxxxx>]

If possible, a EC_KEY_get_public_key_affine_coordinates function would
be appreciated, so we can avoid using
EC_POINT_get_affine_coordinates_GFp. Unless I've missed a better
function to get raw x/y. 

Perhaps also EC_KEY_get_curve_name?  

Angus