Hh inchi

[hhaensel]

Add coordgen! to inchitomol

[hhaensel]

With the latest PR #138 this would be unnecessary. However, the question is still valid, whether we should generate a molecule from inchi without creating coords via coordgen!(). The PR above requires coordgen!() in order to get the stereo right.

[mojaie]

Since coordgen! can be very expensive, I think it would be best to force calculations only when stereochemistry is required.