Moved source files to directory src and changed Makefile for support this.
Created classes Double, Point and Vector for refactoring (realized).
Included parameters thickness and extrusion not yet used in Archimedes CAD (possibility of conversion to others CAD files) and modified pure virtual methods of Builder to only virtual methods.
I have put my name as coauthor in the README and LICENSE files, Point variables  have been replaced  with Vector class for better comprehension of calculus, ellipse conversion to ARC have been implemented with and without rotation, small improvements in readability of the ARCBuilder class and inclusion of ellipse examples in DWG.