Semantics of at are unclear

[noelwelsh]

The semantics of at when combined with our combinators such as beside and above are unclear. For example, this does not render what I expect:

(Circle(10).fillColor(Color.darkBlue) beside 
  (Circle(10).fillColor(Color.aliceBlue).at(10,10) on Circle(10).fillColor(Color.red)))

Specifically, I don't expect a gap between the darkBlue and red circles.

[noelwelsh]

Fixed by commit d863574