Add input and output file to ease regression testing

[monty241]

When changes are made to the model, there is no unit test to verify and/or assess impact impact. Some pre-defined input and output files with possibly edge cases would ease validation of changes.

[RIVM-OPS]

First of all, we'd like to apologise for the late reaction. We'll try to reply more quickly to future issues.
Thank you for your report. Input/output files are available for download from the OPS website: rivm.nl/ops
Unit tests will be added in a future release, see issue #9 for updates on the unit tests.
We will close this issue, as input/output files can be downloaded from the OPS website as stated.