Major debugging in the 'surface - residue distance' routine.
Merge pull request #7 from mlund/master

post-vacation update
Implemented 1/r6 for hydrophobic wall ext. pot.
Minor tweaks.
Forgot to implement textio::powsix
Indentation
Hydrophobic wall: 1/r6 --> fully fledged LJ.
Removed 'powsix' from textio
Final touches.
Teaked LJ to shift the potential minimum towards the close contact point.
Merge pull request #29 from jmhenriques/master

Extended the hydrophobic wall class.