Update Elements.java

Adding a message that the class is generated in the `cdk-build-utils` and static instances are for backwards compatibility.
Don't fail when matching empty structures - this defaults such that an empty structure never matches.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
API changed required to correct VF implementation (non public class)

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Correct VF target vertex selection - if the query vertex is in the terminal set then the target must also be. This will now correctly match disconnected queries.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Check consistent of atom matches in the UIT - C**C will not match SCCS

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