Parametric Nintendo Switch cartridge holder

This is a remix of [rwindr's original cartridge holder for the Nintendo Switch](https://www.thingiverse.com/thing:2633724). Changes include:

* Made a parameterized model in OpenSCAD based on rwindr's original design.
* Added the ability to specify the number of cartridges in the X and Y axis and also to customize many aspects of the print (window size, base thickness etc).
* Increased the default size of the window to accommodate those of us with stubby little fingers.
* Re-designed the nubs that hold the cartridge in-place...not sure if I did a better or worse job than the original or how it will hold up in the long-term, so all feedback appreciated.

The tolerances are a little tight on this, you may want to print a 1x1 first to make sure it's still a good fit with your own printer and then either edit the SCAD file or scale the print accordingly.

Apologies to antwr for posting this so soon after his original upload...I really liked his design and with the holiday season