ENH: simplify use of case-relative paths
- provide relativePath() for argList and for Time. These are relative to the case globalPath(). Eg, Info<< "output: " << runTime.relativePath(outputFile) << nl;
- provide relativePath() for argList and for Time. These are relative to the case globalPath(). Eg, Info<< "output: " << runTime.relativePath(outputFile) << nl;