fixed the generation of the triangle's normal (in case they are undefined or badly formatted) during import (they pointed at the inside of the model before)
fixed the order of vertices when creating a new Triangle instance (clockwise instead of STL's counter-clockwise order is expected)
output a warning once if the direction of the normal does not match the order of the vertices of a triangle (both indicators are redundant and should be consistent)


git-svn-id: https://pycam.svn.sourceforge.net/svnroot/pycam/trunk@710 bbaffbd6-741e-11dd-a85d-61de82d9cad9