BUGS
----
o On Linux, large files load veery slowly
o Some invalid DXF data gets pass the import checks and breaks the tessing code
o Broken polyhedron() entities are not correctly detected and cause CGAL segfaults

USER iNTERFACE
--------------
o Preferences
  - background colors
  - Model outside/inside color
  - wireframe color and width
  - OpenGL params
  - Default language feature settings
o External editor
o Mac OS X:
  - embed examples into bundle -> separate example menu?
  - Use examples as default File Open folder
  - distribute as (self-unpacking?) dmg containing a single .app instead of zip
  - universal binary -> fix cgal and opencsg
o Build multiple variants from one single build? (e.g. without opencsg)
o MDI
  - Think about how to do MDI the right way
  - Quit vs. Close MainWindow.
    Today Quit just closes the current window and there is no close function
  - windowModified property -> windowtitle and check on quit/close
o 3D interaction
  - Improve mouse rotation
  - Add modifier key combos to handle pan on 1 mouse button systems

ENGINE
------
o 2D Subsystem
  - Add support for Nef Polygons and 2D CSG
  - Add import_dxf for loading DXF files
  - Add DXF export for designs with a Nef Polygon as root element
  - Add generic 2D->3D extrude statements
  - Add generic 3D->2D projection statements
  - Support old dxf_extrude statements for compatibility
o Advanced Transformations
  - Add statement for 2D and 3D minkowski sum
  - Add statement for refinement via surface subdivision
  - Add statement for intersections in cartesian product of childs