Zeroed lum in emissivity calculation before adding over all cells. Fixes #59
Enabled reporting of macro atom level emissivities in py_wind
Added P_escape overview for balmer lines in macro atoms
Fixed writing to file of Balmer escape probabilities
Merge pull request #61 from Higginbottom/dev

Merging in ready for release of Python 77, used for Proga paper
Python 77 commit, used for Proga paper
changed version to 77a_dev