Polyomino/Pentomino Filling Example with SAT

[Ben Griffin]

This is a continuation of my learning of OR Tools, where I've been working on various puzzles in order to better understand how to model and implement SAT.

I thought it may be of use (or fun) to some people in this group. Feel free to share accordingly (it's under the  Apache 2.0 license). 

Of course, any suggestions on improving the SAT model/solver are always welcome.