residue_types.txt accumulates input residues at the bottom

[tlfobe]

@izzie-strawn found a bug where running the simple example scripts resulted in a broken residue_types.txt file leading to a quick segmentation fault error when trying to build a pose form sequence.

Looking into the files it seems her copy of CG PyRosetta had a residue_types.txt that no longer had the Rosetta library of residues and had multiple copies of our added residue types.

The current fix is to remove PyRosetta4.modified directory and to reinstall