Add Greg's solcheck

[torressa]

Merge the solcheck code into the modelanalyzer. Also updated to use the gurobi_sphinxtheme, looks much cooler!

TODOS:

• Docs need a second pass.
• Tests are missing for the CLI but I'm not sure how to do this right now.

[gglockner]

@torressa : To test the CLI, you could run in batch mode (with the --model flag), send the output to a temp file, and do a checksum like md5 on that output.

That said, I'm confused why you included afiro.mps and misc07.mps (which are part of the standard Gurobi distribution, though not gurobipy) while you didn't include the sample files afiro.{sol,json} and misc07.sol.

[mattmilten]

Let's merge this now and then fix remaining issues later.