Add an ideal age tracer case to the single column test group

[katsmith133]

This PR adds an ideal age tracer test to the single column test group. It initializes the ideal age tracer to 0 seconds throughout the column and runs the same 1 day simulation as the CVMix single column test. Visualization of the tracer, along with temperature and salinity, a the start and finish of the test are outputted and a comparison of temperature, salinity, and the ideal age tracer are made with a baseline, if provided, for validation.

I tested this case on compy and the following is what I get after a 10 day run for the ideal age tracer: These results are to be expected as an ideal age tracer measures how long it has been since a parcel of water touched the surface. Here, water at the immediate surface is zero seconds, at depth is 864000 seconds (10 days), and between in the mixed layer there are values in between.

Checklist

• [x] User's Guide has been updated
• [x] Developer's Guide has been updated
• [x] API documentation in the Developer's Guide (api.md) has any new or modified class, method and/or functions listed
• [x] Documentation has been built locally and changes look as expected
• [x] Testing comment in the PR documents testing used to verify the changes
• [x] New tests have been added to a test suite

[katsmith133]

@xylar I've made the last changes and tested them, so I think its ready to go!