add interppotential extension
start on new implementation
calculate a potential in C
fix array access
add python potential evaluation
calculate spline coefficients in C
free memory
add interp2d files
change how potentials are called to allow the interpolated potential to be called; add NULL pointers to the potentials that do not use the interpolation
add members for interpolation
change to use the new way of calling potentials
parse interpolated potential
also save the log grid
edit how the interpolated potential is calculated using the new method of calling potentials
edit for new method of calling potentials
correctly compile new functions
add README
C implementation of interpolated potential