Option for emitting all integrator time steps

[rruusu]

Current status

Currently OMSimulator only emits data into the result file using a fixed time step size, either based on the maximum time step size or the number of intervals provided by the --intervals option.

Feature description

It is sometimes useful to get output that shows all steps made by the variable step solver, especially for debugging purposes.

One option for expressing this to OMSimulator could be by setting --intervals=0 on the command line.