updated hydrogen accounting and aromaticity

[fgrunewald]

This one updates the h accounting and aligns it with the latest pysmiles aromaticity version. Overall, the largest change is that things like imidazole, when written incorrectly using the aromatic shorthand, will raise an error. The rest is just cleaning, which is made possible by the new pysmiles code.

To Do

• [x] catch error and print some more explanation
• [x] wait for pysmiles to be updated