Wrote FBLS.

This function performs the convolution after the points are
folded. This means that the FFA is only run once per period block, but
the each convolution takes 2*N sums per block, so the savings we're as
big as I expected.

I might be able to increase the speed more if I am careful about the
modulus operators, and type-convert the DelT parameter outside of the
loop.
changed setup.py to incorporate FBLS algorithms
Tried to get FBLS to compute the s2n for each epoch. I'm getting weird
spikes of high S/N and I don't know why

- numerical instability with sigma?
- They seem to be coming from exceptionally low values of sigma
savinbg
modifications