The structures with atoms with valences rendering incorrectly after saving

[AlexanderSavelyev]

Steps to reproduce

1. Launch application
2. Create any structure, for example, chain.
3. Double click any structure carbon atom.
4. In the opened "Atom properties" window select Valence 0 (zero). Click OK.
5. Click "Save as" button.
6. In the Format field set "Daylight SMILE". Click "Save to file" button.
7. Clear the canvas.
8. Open saved in 6th step file.

Actual result
The atom with added valence is replaced with diradical (singlet).
Other variants show in the table:

Valence\Format	MOL	Daylight Smile	Extended Smile	Daylight SMART	Inchi	Inchi Auxinfo	CML
0	OK	is replaced with diradical	disappears	Can't be saved	disappears	disappears	disappears
1	OK	is replaced with diradical	disappears	Can't be saved	disappears	disappears	OK
2	OK	is replaced with diradical	is replaced with diradical	Can't be saved	is replaced with triplet	is replaced with diradical	OK
3	OK	is replaced with monoradical	is replaced with monoradical	Can't be saved	is replaced with monoradical	is replaced with monoradical	OK
4	OK	disappears	disappears	Can't be saved	disappears	disappears	OK
5	OK	OK	OK	Can't be saved	OK	OK	OK
6	OK	OK	OK	Can't be saved	OK	OK	OK
7	OK	OK	OK	Can't be saved	OK	OK	OK
8	OK	OK	OK	Can't be saved	OK	OK	OK

This table is about carbon atom. For other atoms it can be different behavior.

Expected result:
The structures with added valences should saved and opened as they were created. In the case if such structure can't be saved the warning message should appear and warn user that the valences can be lost after saving.

[Ksanjara]

Warning message:"In Daylight SMILES valence is not supported" appears, but if User save structure in .smi or .inchi format (according to the table) and then open it - atom with valence rendering still incorrectly as at actual result description.

[AlexanderSavelyev]

it make sense to revalidate the task and return warning messages for specific formats if explicit valence is not supported