Added option to put pdbqts into subdirectories

[allisonbarkdull]

No description provided.

[diogomart]

Modified to write zipped (.tar.gz) files with 10k PDBQTs each. Command line options are

• -z / --multimol_targz triggers tar-gzeeing
• --multimol_targz_size to set the number of PDBQTs per .tar.gz (default is 10k)

Additionally added --name_from_prop for SD files that store the molecule name in a property, such as > <mol_id>, instead of storing in the designated name field, which is the first line of the MOL block.