- replace the array (curves, stitches, threads,...) by list to be more flexible with delete and moves of elements
- refresh curves only when needed

declare dependents objects to their reference (to be able to remove the reference without error)

- move the maxlen attribute to OE_stitch class with a stitcchMaxLen funct (every child class can use it)
- add a defaultLinkMaxLen for the linkstitch class
- remove start and end attribute in linestitch (subcurve class make them obsolete)
- add get functions for curves in OE_controller class

add a new subcurve class (parametric subcurve) and a joincurve (concatenate curves)

add thread class (stitch one, not computing) to deal with color, width and later (maybe) rendering style

second move to a MVC design

add a OE_svgParser class to fill the document
first move to a MVC design