I know there is a user created patch that allows you to place VBL on tokens at the moment - but it hasn't been included in the main build and I'm sure it won't be until 1.4. This would allow VBL to be automatically laid down when you lay down a wall tile for example. Right now, you just have to lace it yourself, but as long as the tiles snap over the grid lines rather than along them, this should work really easily. It would also allow VBL to rotate as a door image rotated.
I'm not sure I see the value in knowing when a door is open or closed beyond the visual element? Right now, as RP says, you can rotate doors around a hinge. I would say that this is enough for DMs - surely they can see when a door has opened too far and make sure they don't rotate it into the wall and so avoid the need for more coding.
Here's an example door image:
Drop this in maptool on the object layer. Ctrl-Shift-middle mouse button to rotate the door. It should rotate around the hinge. Apart from having VBL track the rotation, I don't really see a need for much more sophistication here - especially not from a mapmaking point of view.