Unit system cleanups

I wanted a better way to define a context dependent rate, which motivated the last patch. (for the keywords which have a "ContextDependent" dimension in some field, the higher level code needs to do the unit conversion and thus I added a few compiler warnings to the schedule code. Also be aware that I might have missed a few keywords due to my limited familiarity with the ECLIPSE format.)

The remaining patches are just renames of dimensions to make the unit system more consistent. (Today, I was sufficiently annoyed by this to take action.)

If you want me do split this PR up and do it "One at a time", just let me know...