Feature request: obs_seq file splitting program

[nancycollins]

Use case

People frequently need obs_seq files split into multiple files that each cover a shorter time period

Is your feature request related to a problem?

we currently point people at a variety of shell scripts. all of them are pretty incomprehensible because they have to do math with dates and convert between gregorian time (day/seconds since 1601) and Y/M/D/H/m/S time formats. also, they use 'sed' to edit an input.nml to set the output filenames and start/stop times for each run of the obs_sequence_tool.

Describe your preferred solution

A splitting program could hide all the date manipulations and be simpler to run. I wrote up this proposal document for how a program like this could work. The 'advance_time' program is a heavy inspiration for how to specify time intervals and output filenames.

Describe any alternatives you have considered

we can exist as we always have with shell scripts, but they're hard for users (they're often hard for me and i wrote a billion of them).

[hkershaw-brown]

Possible dupilcate/overlap https://github.com/NCAR/DART/issues/226

[hkershaw-brown]

merged this issue into #226