Split label field in separate internal and public field. Public field
should never be changed by HEM_Machines and should be propagated across
edge and face splits.
1. Added copyProperties() to HE_Face, HE_Vertex and HE_Halfedge to
simplify future changes.
2. Added various setColor functions to HE_Mesh
3. fuseCoplanarFaces() now takes face properties of first face in planar
set for new faces.
4. added selection methods with internal label and renamed relevant
functions to blaWithLabel, blaWithOtherabel, blaWithInternalLabel and
bla WithOtherInternalLabel
Fixed bug that resulted in wrong triangulation of concave quads.
Fixed HEM_Bend
1. Cleaning label related code
2. Considering poly2tri
Added HE_Machine interface to HEC_Creator
Fixed STL and OBJ export bug "dumb coder forgetting to check if
directory exists".
Merge pull request #14 from wblut/internallabel

Internallabel