Added Timer Example

Added a Timer example to the MainLoop. The new classes are part of the
example.

And corrected a few minor things:
Shutdown request should now work as intended.
TimerManager should receive requests correctly when more than one
TimerServer is present.
Loop counting is now separate from the 10-loop cycle used by the average
FPS calculation.
Simulation speed should work properly.
Simulation time should be calculated properly.