When ring membership is specified without a number, match any ring atom. Resolves bug 1168.

Change-Id: I3828029dcb4de440af630a30e1946d5438bab9e7
Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>

Conflicts:
	src/main/org/openscience/cdk/isomorphism/matchers/smarts/RingMembershipAtom.java
	src/test/org/openscience/cdk/smiles/smarts/parser/SMARTSSearchTest.java
Resolution for bug1269 - stop the hydrogen placer attempting to place hydrogens on null atoms.

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

Conflicts:
	src/test/org/openscience/cdk/layout/StructureDiagramGeneratorTest.java
Tidy up of HydrogenPlacer including test annotations and additional assertions about placed/unplaced atoms.

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

Conflicts:
	src/main/org/openscience/cdk/layout/HydrogenPlacer.java
	src/test/org/openscience/cdk/layout/HydrogenPlacerTest.java