Provide stream that ignores everything written to it

Use this stream when you want a straight code path, but also be able
to disable output at will.
Disable output to console if parameter quiet = true

If the standard output is not desirable, it can be suppressed and
custom output can be written through the timestep_completed event
instead.
Merge pull request #392 from rolk/392_quiet

Add option to suppress output in SimulatorIncompTwophase