ConfigOutput is not behaving as expected or hoped

[timspainNERSC]

1. The logged output times are not the true output times
2. Given a model start time and output start time of 00:00 the first output occurs at 00:10, i.e. after 1 model timestep. It then recurs with the correct frequency. If the desired frequency is once per hour, output occurs at 00:10, 01:10, 02:10 &c.
3. The infrastructure now exists (in ParaGridIO) to output more than one time sample into a file. When ConfigOutput is being used it should be able to assume that this is possible and not generate a new file at each output time.
4. The output frequency and the frequency of opening new IO files should both be separate and specifiable.

[timspainNERSC]

Item 1 ✅
Item 2: Output only happens when the end of a timestep exactly equals an integer multiple of the time since the last output. That is, starting at midnight and requesting output every hour will only output when the end of a timestep exactly coincides with an hour. Eleven minute timesteps and hourly output would only output at 11:00, 22:00 etc. So, ✅
Item 3 ✅

[timspainNERSC]

The code to fix this is present in the branch jun23_demo and its descendants.

[timspainNERSC]

With #383 and #428 merged into develop, this issue is fixed.