Emulated DLR Test failures

CT22 provides a new emulated DLR test. During testing with the CT22 beta, several bugs were discovered in the stack's DLR state machine.

• If a ring fault occurs, e.g., due to a link loss, the ring status attribute jumps back and forth between normal and fault until the ring is healed again.
• Forwarding of overflowed sing_on frame does not work
• Neighbor check retry does not work properly. In case a neighbor check was run before, the next time not all 3 retries are performed.