CXSmiles isn't properly escaping floating point properties

[bp-kelley]

Example structure

The Chemaxon smiles that rdkit generates is:

O=C(O)CCCCc1cccc2cncn12 |atomProp:1.apKa.4.2:14.apKa.7.54|

Note the second . should be escaped (even though the Chemaxon Docs clearly says that it doesn't for properties)

OC(=O)CCCCc1cccc2cncn12 |atomProp:1.apKa.4.2:14.apKa.7|

The escape code for '.' is .

We do parse it properly though.

>>> m = Chem.MolFromSmiles("OC(=O)CCCCc1cccc2cncn12 |atomProp:1.apKa.4.2:14.apKa.7|")
>>> for atom in m.GetAtoms():
...   if atom.HasProp("apKa"): print(atom.GetIdx(), atom.GetProp("apKa"))
... 
1 4.2
14 7