Line now uses new style methods - not ready to merge yet

Hi all,

This one was pretty straight forward, no problems. It did highlight for me the value of getting instance variables for styles since I changed a bunch of instance variable calls to method calls which look up style (I'll point that out in-line).

I also removed the `gui_opts` because it doesn't look like we're using those. I'll point that out in-line too.
It seems that when `redrawing_aspect` calls for the line to be redrawn `positioning` calls `update_gui` on the swt backend ([code](https://github.com/shoes/shoes4/blob/master/lib/shoes/common/positioning.rb#L17)).

So I bumped the @transform stuff all down to `translate_according_to_enclosing_box` and had the whole thing called on `update_position`. I'll be there's a reason the two were separate before though (hence my calling this a hack).