Does anyone know of a general purpose vector graphics editor that allows editing within a specific width and height and all movements are mirrored - somewhat like the ship editor for XPilot ?

Pretty much any vector editor will let you do that. Give Inkscape a try, it's free.

Unfortunately that isn't what I'm looking for - It wont export to ASCII X & Y coordinates (SVG is no use and produces too much unneeded stuff).

In addition, you can't set a handle position, for which these coordinates are offset (important for positioning and scaling).

Finally, you can't define areas of the object with attributes.

If you can program a game, you can easily program a converter from SVG, which is one of the simplest and most documented graphics formats in use, to whatever you need.

Usually its too much trouble writing convertors - plus, of course, you need to need to deal with whatever coordinate system the package uses.

However, I've written my own vector program now so its all sorted :)