Changed update system and made general improvements.

In Server, Client, and all time dependent Activities the updating system was changed from being
based on nanoseconds to being based on ticks.  These ticks are converted from elapsed nanosecond
time in the game loop. The construction of InputManagers in SpaceshipServer and SpaceshipClient
(renamed from BumperCarServer and BumperCarClient) was tightened up.  Also, the Client now uses
a MessageBuffer to avoid multiple Message writes from different Threads, which resulted in a bogus
read at the client side.