Add option to write time intervals in the .geo writer

Please add the option in the .geo writer to output intervals of timesteps, such as 1,5,9, etc. This will allow users to run multiple jobs in parallel. I also want this writer to be able to write a range of timesteps, such as timestep 40 to 80. We are having jobs that are large enough that we are timing out on the clusters before the last frames get written out.

I tried using the Extract Time Step filter, and this doesn't do what is requested. I want output files to be numbered 1,5,9, not 1,2,3.