Daylight SMILES General Chiral Specification

**Background**
Current smiles loader implementation doesn't keep general chiral information represented with AL, TH, SP, TB and OH labels.
The chiral information is used only as a hint to mark stereocenters.

**Solution**
Indigo should keep the chiral information and have possibility to pass it to ket-format.
Smiles saver should also use the information to recreate original SMILES with general chiral data.
For instance the following SMILES: F[Po@SP2](Br)(Cl)I after conversion to KET and vice versa should keep the same representation.