- run-time warning about deprecated features. For example,

  DeprecatedInFunction(2212)
     << "Prefer using xyz boundary condition. "
     << "This boundary condition will be removed in the future." << endl;

CONFIG: mark exprFixedValue as deprecated

- same functionality is possible with uniformFixedValue and an
  expression PatchFunction1, which can also be easily changed to any
  other PatchFunction1