Move math functions to a separate module
Add line plotting to grid
offset, scale, boxToOriginAndExtent added to math module
Remove size, origin from grid

Math module takes care of that, we are operating in terms of integral
grid only
rectangle object with merge, extend, box methods
Change rectangle box calculation - not sure if that's correct
finding rectangles added to grid

Added horizontal and vertical findBoxes functionality
Implement plumper in terms of grid coordinates
Use spaces for indentation