o now with a twist :)
o as well suggest negative twist values.
o smallish tweaks.
o update usage in readme.
o Move printng in separate class.
o Add postscript printer.
o Add option to print to PostScript.
o Update doc with postscript.
o basic transformation into polygon extruding.
o re-add template based screw function.
o read arbitrary polygon from file.
o Make 'make clean' remove objects.
o rename 'radius' to 'initial_size' to better reflect its use.
o calculate radius from polygon for offset reasons.
o more robust reading of polygon.
o move polygon offset in separate file.
o do offset the CGAL way.
o add pump parameter.
o Add a Matryoshka mode to better gauge the fit in postscript mode.
o Do not go down until we have reached the new position.
o separate Init() from Preamble(), so that we can put the comments
  at the right places.
o Improve and simplify polygon offsetting by not using CGAL but
  Clipper http://sourceforge.net/projects/polyclipping/
o Update license for clipper lib.