Fixes TCP control flow (test case 1 working)

Previously, the simulation would not terminate, since routing updates
never stop, so I added a transmission finished event to the TCP
algorithms, which is only successful once all packets have been
transmitted successfully.  Network.simulate uses these events to
terminate the simulation once all flows have finished.  Also fixed a bug
in FAST TCP; since the timeout was too small (in test case 1), FAST was
retransmitting packets that were still in transit, creating a loop of
transmission events for ~3 packets.  Now, both FAST & Reno work for test
case 1 (or at least transmit their data successfully; I have yet to
monitor them for correct behavior)