Kinect/3D Scanner Calibration Pattern

This OpenSCAD script will generate a grid pattern of small cuboids attached to a large flat cuboid.

The heights of the smaller cuboids will alternate sequentially.
The user can specify the number of rows & columns as well as the length & breadth of the smaller cuboids and the separation between adjacent cuboids.
The Number of different heights and the difference in height between smaller cuboids can be specified too.
The user can also choose whether or not to add Keyed connectors so that t