o Reset E0 in the beginning.
o Allow to choose miter type for offsetting.
o make steps in preparing the polygon a bit more readable.
o Rename Point2D to Vector2D
o Instead of pair<float,float> in the parameters, use a
  Vector2D, which is more readable.
o use Vector2D instead of manual listing of x, y parameters
  in printers.
o more replacment of individual variables with vectors.
o Update README with current options.
o Don't write 'value' for things that use an optional value
o Nicer grouping of options; more headlines in-between
Merge remote-tracking branch 'upstream/master'