box API for SCAD

## Introduction

This thing is just a SCAD script that provide an API to manipulate parts of a models by placing them relative to each other.

When writing SCAD models i found out that the result scripts are not readable. Even when i read them myself many days later i don't understand what i wrote and why i wrote them this way.

The main reason is that i use a lot of constant values computed or measured on parts in real life and even with comments in code this is hard to read. Furthermore when i want to make modifications i don't know where to apply them in code.

This API simplify all my designs by allowing me to place parts relatives to each other.
This thing is designed using this library: http://www.thingiverse.com/thing:2005142

## How it works

### Boxes basics

Each elementary part of the model (cube, cylinder etc...) can be bounded by a box that you create using the api `boxCreate()`.
Boxes faces are always aligned with x,y,z axis. The boxCreate api just take t