[ODE] Plane2d

[Chris Jefferson]

Hello!

I'm currently working on a project involving 2d and have been using 
plane2d with great success. I was wondering why it can't get merged into 
the main ODE CVS?

Possibly connected to why it can't get merged, the current code doesn't 
correctly handle some rotational issues which have to be correctly 
manually. I had a quick look around code for the other joints and trying 
to fix this is beyond me, but it looks like it should be fixable. Out of 
interest, how long would it take someone with much more ODE knowledge 
than me to fix this?

Thank you,

Chris