Major update to GammaInc

GammaInc function now supports negative values for 'a' in GammaInc(a,z)

In model_halo : allow for NH variation and keep d2g
Use my halo calculations as a single library?

added __init__.py to allow for possibility of importing all of my halo
library
Can now import halo_lib

by updating __init__.py file
model_halo no longer requires aeff

or asciidata or radprofile
Cleaned up version before making analytic halo faster

I think it works.  (Running test code now)