Functions to calculate dimensions and spans.
author  Mark Raynsford

Return the span on the X axis of the inclusive range defined by the given
points.
param  lower
The lower point
param  upper
The upper point
return  upper.getX() - lower.getX()) + 1

Return the span on the Y axis of the inclusive range defined by the given
points.
param  lower
The lower point
param  upper
The upper point
return  upper.getY() - lower.getY()) + 1

Return the span on the Z axis of the inclusive range defined by the given
points.
param  lower
The lower point
param  upper
The upper point
return  upper.getZ() - lower.getZ()) + 1

Given an inclusive range defined by [low .. high], split the
range in the middle and produce two new inclusive ranges.

The lower and upper bounds of the lower range are stored in
out[0] and out[1], respectively. The lower and
upper bounds of the upper range are stored in out[2] and
out[3], respectively.

@param low
The lower bound
@param high
The upper bound
@param out
The output vector