When will smiles be randered as Kekule structrue and when will not?

[Valen-C12]

And can we config it to always (not) use kekulize?

[Acylation]

Seems like only when all carbons in the ring in lower case will the ring be aromatized.

[luokui-c12]

smiles should be kekulize mode

[xavierholt]

Here are some more test cases. My summary of the current behaviour:

• Rings only draw as aromatic when all the atoms (not bonds!) that make up the ring are aromatic (lower case).
• Double bonds draw as half-dashed aromatic bonds when they're both a) between aromatic atoms and b) in rings.
• Explicit aromatic bonds (:) draw as single bonds; I can't figure out how to draw one that's not part of a ring.