1) VTK-style comments on all the methods in the .h file.  I have
no idea what I was thinking (or not) when I forgot to do these.

2) Copyright changed from Sandia to VTK standard.

3) Added #include <cstdlib> to TestExecutionTimer.cxx to make sure
EXIT_SUCCESS is defined.

4) Condensed the output from the test.

5) Replace the guts of the test with the guts of the vtkDelaunay2D
test so that it takes a little while longer.

6) Switch the output to 8 digit fixed precision to make it much
less likely that times will be rounded to zero.

Change-Id: Ic6b86fc5645d979fbeacca22f8bb68990ecc3890