Doc work GEE, GMM, sphinx warnings

add GEE to docs
improve GMM docs, add new classes

fix some spinx warnings
   var_plots truncated year string
   seealso VAR documentation gave `invalid option block` warning

I upgraded sphinx to version 1.2, I'm still not building notebooks and didn't check those.

GEE still needs proof reading and example in gee.rst
GMM and sandwich covariances still need improvements