Added BenchmarkSwtMultithreading #74

[jukzi]

To show the impact of many messages to

org.eclipse.swt.widgets.Synchronizer.addLast ()
org.eclipse.swt.graphics.Device.isDisposed ()
org.eclipse.swt.widgets.Synchronizer.asyncExec ()
org.eclipse.swt.widgets.Display.findDisplay ()

[jukzi]

this test schedules 1 Million trivial events.
Without #77 it does not finish anytime soon. While with #77 it finishes quickly printing like.

Duration for scheduling:     250.443.500 ns  handling:     254.198.000 ns
Duration for scheduling:     206.964.300 ns  handling:     233.658.400 ns
Duration for scheduling:     165.361.400 ns  handling:     207.411.000 ns
Duration for scheduling:     133.456.100 ns  handling:     206.118.800 ns
Duration for scheduling:     137.097.000 ns  handling:     202.650.900 ns
Duration for scheduling:      33.593.800 ns  handling:     204.759.700 ns
Duration for scheduling:      34.982.300 ns  handling:     202.305.200 ns
Duration for scheduling:     125.717.000 ns  handling:     205.349.900 ns
Duration for scheduling:      25.936.000 ns  handling:     206.072.200 ns
Duration for scheduling:      26.510.100 ns  handling:     203.859.700 ns
Duration for scheduling:      82.233.100 ns  handling:     203.064.000 ns
Duration for scheduling:      25.010.300 ns  handling:     203.906.400 ns
...

[jukzi]

with #75 i see a reduction in handling from 203 ms ->190ms :

Duration for scheduling:     255.251.400 ns  handling:     213.363.800 ns
Duration for scheduling:     197.382.200 ns  handling:     195.838.500 ns
Duration for scheduling:     163.338.800 ns  handling:     195.872.300 ns
Duration for scheduling:     132.593.000 ns  handling:     190.864.300 ns
Duration for scheduling:     113.605.500 ns  handling:     189.024.500 ns
Duration for scheduling:      33.007.700 ns  handling:     189.700.600 ns
Duration for scheduling:      33.174.100 ns  handling:     191.078.500 ns
Duration for scheduling:     127.557.800 ns  handling:     190.284.900 ns
Duration for scheduling:      28.377.600 ns  handling:     189.561.600 ns
Duration for scheduling:      25.562.600 ns  handling:     189.653.400 ns