fix menubar position when header is not shown
Replacing Vaadin messagebox with confirmdialog and fixing theme.
Fixing ConfirmDialog's messages

The ConfigDialog expects a plain text content not an HTML content.
Added other minor fixed to some classes.
make a test case that checks all top-level menu items
fix a problem with invalid linkd files that set a vertex as its own parent
Merge branch '1.12'

Conflicts:
	features/topology-map/plugins/org.opennms.features.topology.plugins.topo.linkd/src/main/java/org/opennms/features/topology/plugins/topo/linkd/internal/LinkdTopologyProvider.java