Code working as it should after minor changes.

Now the network adapts well to link failures/recoveries: now the SONET
router sensing the failure (1) sends a FAILURE_EVENT_COMMAND to each
other router, making them RESET the info on their routing tables;
(2) RESETs its own routing table; (3) sends RESUME_RESTORATION_CMD SONET
frames to every other router in the network, making them send
TEST_LINE_CMD signaling frames (the initiating router also calls
resumeRestoration() when finished sending all the
RESUME_RESTORATION_CMD.

All in all, this increases the complexity to: 4 * (N - 1) + (4 * (N - 1)
* 4 * (N - 1)), 4 * (N - 1) + 16 * (N - 1)^2, i.e. still O(N^2) complexity
in terms of exchanged messages.