Implicit hydrogen count should always be 0 or greater.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Ensure an exception is not thrown when a tetrahedral centre has an implicit hydrogen by the target does not. We want matching to be consistent whether the query as implicit/explicit hydrogens and so we say this is not a substructure match (with stereochemistry).

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Remove deprecation warning - this will likely be the best way to set the parameters for SMARTS for a while.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Point to correct usage in error message

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>