Add biopython.egg-info to git ignore list
Use system temp for test_SeqIO_index.py index files
Move one-to-three protein letter maps into Bio.Data.IUPACData
SeqUtils.seq3 now creates a copy of the imported IUPACData dict

This is to prevent a bug where the IUPACData dict is imported in some other
modules, and the key-value pairs have unexpected values due to seq3's update.
Move Bio.SCOP.three_to_one_dict to Bio.Data.SCOPData