[with patch; positive review] modular symbols -- optimize fast computation of hecke eigenvalues on weight 2 modular symbols for gamma0

[was]

1. Implement applying Hecke operator to a single sparse vector, an operation that is needed for quick computation of systems of Hecke eigenvalues.

2. Make very very fast code for applying many Hecke operators to a single vector with one nonzero entry.

NOTE: The higher weight patches (starting with patch 10) depend on upgrading flint, since flint had a bug: #3523.

NOTE: A cumulative bundle with all possible dependencies is here:

 http://sage.math.washington.edu/home/was/patches/3502.hg

[craigcitro]

So I looked over the code, and everything looks good. There were a handful of small touch-ups needed, missing doctests, etc., so I went ahead and took care of all of that. Someone should look over the additional patch I've posted, but after that, this looks ready to go.

I'm also cleaning up the ticket by deleting the 12 individual patches and posting William's complete bundle (from the URL he added above), and adding my patch.

[craigcitro]

William's bundle with all patches

[craigcitro]

(This doesn't need to go into 3.1.2, so I'm moving it to 3.1.3.)

[was]

I read through the additional patch, applied it, doctested it, and I'm happy across the board. It's very good for increasing doctest coverage.

Thanks Craig!!

[mabshoff]

Merged 3502.hg and trac-3502-addl.patch in Sage 3.1.3.alpha1