*.smi file format

[frazierbaker]

Hi there!

Thanks for the contribution. I think this will save me a lot of time.

Do you think that it would be possible to update the documentation to specify the expected file format for *.smi files? I expected they were just text files with one smiles per line, but it appears that a whitespace and index is also required on each line. For example:

This is a valid *.smi file:

valid.smi

CCO 1
CC=O 2
CCC 3
...

whereas this is not:

invalid.smi

CCO
CC=O
CCC

It might also be worth loudly failing in these cases, as currently the fpsim2-create-db script simply creates an empty database. Alternatively, you could support SMILES-only text files with an auto-incrementing indexer.