Better diagnostics for OpenFOAM errors/warnings

Support for custom errors/warnings

• Currently, worrying about warnings is not a priority, but it should become important at some point
• It would be nice if users can write their own regular expressions for parsing their custom error messages
• Adding support for running specific utilities is a plus, examples include:
  • checkMesh to warn users their mesh is not good
  • setFields to catch errors in setFieldsDict

Alternatives Currently, each error message (the whole content of stderr) is parsed with a single regex. An alternative is to extract needed pieces of information using separate regexs; but I can't decide which is better.