ENH: boundBox 'reduce' method (related to #196)

reduce()
- parallel reduction of min/max values.
  Reduces coding for the callers.

  Eg,
      bb.reduce();

  instead of the previous method:
      reduce(bb.min(), minOp<point>());
      reduce(bb.max(), maxOp<point>());

STYLE:

- use initializer list for creating static content
- use point::min/point::max when defining standard boxes