Add a TERSE option to SKIP_STEADY_STATE setting

[MitchHeineman]

When a user implements SKIP_STEADY_STATE either via steady-state flow conditions or using the EVENTS feature, the model outputs long stretches of constant outputs for its hydraulics that are not of interest during post-processing. Adding a TERSE option would eliminate output during these periods, which could yield substantial savings in output file sizes and thus post-processing times. A suggested syntax for SKIP_STEADY_STATE is shown below. I submitted code for this to EPA in 2015. It was quite simple to code at the time. Such a change would also necessitate a change to the GUI, which currently reads the initial date/time and timestep in the output header section but ignores the timestamps for subsequent records.

• NO – calculations are performed at all timesteps, and all requested output is saved at each reporting timestep.
• YES – toggles steady state based on specified flow tolerances unless an [EVENTS] section is present in the input file. If [EVENTS] are specified, then routing calculations are only performed on specified dates, with constant flows in conduits (from last dynamic simulation step) during intervening steady-state conditions.
• VERBOSE – identical to YES
• TERSE – same as YES/VERBOSE except that no output is written to the binary output file during steady-state