ENH: Added new multiRegion function object

Wrapper that clones the supplied object for each region.

Simplifies setting up identical post-processing requirements for multi- region cases. Applies the supplied function to all regions by default.

Example of function object specification:

multiRegion
{
    type            multiRegion;
    libs            (utilityFunctionObjects);
    ...

    function
    {
        // Actual object specification
        type            fieldMinMax;
        libs            (fieldFunctionObjects);
        fields          (<field1> .. <fieldN>);
    }

    // Optional entries
    regions         (region1 region2);
}

Where the entries comprise:
    Property     | Description               | Required    | Default value
    type         | Type name: multiRegion    | yes         |
    function     | Function object sub-dictionary | yes    |
    regions      | List of region names      | no          | all