Fixes for general expectation computation.
Fixes for general expectation computation.

mrshirts/pymbar,choderalab/pymbar,jchodera/pymbar,kyleabeauchamp/pymbar,wesbarnett/pymbar,wesbarnett/pymbar,wesbarnett/pymbar,Lnaden/pymbar,choderalab/pymbar,choderalab/pymbar,kyleabeauchamp/pymbar,kyleabeauchamp/pymbar,kyleabeauchamp/pymbar,Lnaden/pymbar,mrshirts/pymbar,jchodera/pymbar,wesbarnett/pymbar,mrshirts/pymbar,Lnaden/pymbar,jchodera/pymbar,mrshirts/pymbar,jchodera/pymbar