some non-catastrophic RuntimeWarning(s) to consider capturing

[moustakas]

For your consideration to capture:

/usr/local/lib/python/tractor/galaxy.py:778: RuntimeWarning: invalid value encountered in double_scalars
  return 4. * ef / ((ef + 1)**2)

and

/usr/local/lib/python/tractor/lsqr_optimizer.py:435: RuntimeWarning: invalid value encountered in greater
  I = (np.abs(vals) > (FACTOR * mx))

[dstndstn]

I think these are BS from the Intel numpy library.