Documentation of Inchi methods

[malteseunderdog]

The documentation of the Inchi methods in the rdinchi module should be improved.

More specifically:

These methods (MolToInchi and InchiToMol) return a tuple, but we have no inkling of the structure of the tuple (e.g. 0th element is the inchi / mol, but what are the 1st and 2nd elements?).

MolToInchi(...) needs a link to page 22 of http://www.inchi-trust.org/fileadmin/user_upload/software/inchi-v1.04/InChI_UserGuide.pdf for the options specification. Also, the spec here is ambiguous with -opt for Linux and /opt for Windows -- how should one specify the options?