Add optional vent holes to lid.

[lemgandi]

Loved this library. But when I passed "ventHoles=true" to the "enclosureLid" call, nothing changed. I added code to create holes over the pins in the lid when you generate "enclosureLid(ventHoles=true)". This will also make it easier to connect a cased Arduino to outside sensors or actuator controls.

I have printed an Uno lid successfully with this mod, and I examined it on a couple of different wall thicknesses and board types. You know the code better than I do though, so I may not have covered every possibility.