typos in mkrpa2.py
Data directory added
Removed unneeded data files
Utility routines moved to a separate file
Density calculation routines are now in density.py
Iteration loop reworked
Fix? in coulomb.py (prefactor). Move data file to data/
Set U0=0 if undefined
U0 renamed to Uext
Added the integral from Rmax to infinity in Coulomb kernel
bug in view-iter.py
Use a different implementation of Coulomb kernel.

Something is subtly broken in the old version, presumably,the behaviour
at the boundaries.
Cosmetic changes, uncommented some corrections