Relative positioning uses wrong y coordinates

[JeanMertz]

Unknown why this happens currently (still adding more tracing and tests), but when using relative positioning, the place that is relatively positioned to another place, is positioned at an unexpected offset.

As an example, this DSL:

place Foo
	My Affordance

place Bar
	Another Affordance

	position > Foo

This instructs the Bar place to be rendered to the right of the Foo place, which means it should use the same y coordinate as Foo, but it's x should be offset to the right of Foo.

Instead, the y coordinate is slightly shifted downwards.