Tweak linux installation instructions.

The RestructuredText formatting got messed up by a line break.
Allow partial matches on truncated InChIs in QM log files.

Some QM programs truncate the InChi when printing the log file,
making the "check the inch is what you were expecting" algorithm
fail. We now allow a partial match (but print a warning). 
(Partial match means everything that *is* printed must match, but
this needn't be the full InChI)