ENH: Added new AMIWeights function object

Reports the min|max|average AMI weights to text file and optionally writes VTK surfaces of the sum of the weights, and mask field for ACMI patches.

Example usage:

AMIWeights
{
    type            AMIWeights;
    libs            ("libfieldFunctionObjects.so");
    writeControl    writeTime;
    writeFields     yes;
}