Renamed isStarted to hasStarted, added getter

Changed Client to a final class
Changed Client and Server to final

Added hasStarted() and overrides for start() and run() to Server
Forgot to save Client prior to last commit so it has final methods
instead of a final class (this commit fixes that)
Migrated buffer methods to a separate class in the common package

The buffer methods were an obnoxious nearly 800 line addition to the
GLHelper method and aren't specific to GL