OpenSCAD functions for generating PCB mounts

Two functions for use in designing cases for PCBs.

Define the board size and drill hole positions with an array, then use one function to generate the board mounts and another function to add a dummy board so that the placement can be tested.

e.g.

myboard = [ 50, 105, //Board size - x,y
10, 10, //Now list x,y positions of board drill holes
40, 15,
15, 80,
35, 90];

board_standoffs(myboard);
dummy_board(myboard);