Elliptic modular functions

[Andreas Enge <andreas.enge@inria.fr>]

Currently, the only modular function that is exported is ellj, but
many others are essentially computed along the way or are hidden in the
source code (double eta quotients, for instance, as used by quadhilbert).

Do you agree that it would be a good idea to export these and other functions?
Concretely, I am thinking of
elldedekindeta, ellweber, ellweber1, ellweber2, ellgamma2, ellgamma3.

If yes, I would be willing to work on it as well as on optimisations and
further functions (at a very leisurely pace, though).

Andreas