pcb enclosure library

This thing is mainly a refactoring from the very good library OpenSCAD-Arduino-Mounting-Library / arduino.scad from kellyegan ( https://www.thingiverse.com/thing:64008 )
This library uses tbuser’s pin library for the pin mounts: http://www.thingiverse.com/thing:10541

At first I used it to print boxes for arduinos. Then I began to add designs to the library to make boxes for Grove shields. After four or five additions, it began fastidious to add to new designs to the global variables of the main file of the library.

This lead me to do this refactoring.”