test PDB cif directory name should be clearer
What
- currently the directory with test PDB CCD mmcif files is called
data/cif
- lets rename it to
data/pdb_ccd_mmcif_test_files
- Consider how many times does the directory name appear in the code?
- Read wikipedia page https://en.wikipedia.org/wiki/Don%27t_repeat_yourself
- Please improve the code.