Merge pull request #2 from D3DEnergetic/rotate

Rotate grid along beam
Create README.md
program description and references
proper spacing
correct citation
added compilation instructions
Fix markdown syntex
added warning
do not interpolate for rho_grid values gt max(rho)
use last value of zeff for rho_grid values larger than rho max
make d3d_chords useful outside of fidasim
update plotting routines
addition changes by bill and bremstrulung routines
forgot to change augd_routines