fix up a few more functions.  typechecks now.
work on some QDiagram instances.  Enveloped is a problem.
add another note about Enveloped
Traced has the same problem as Enveloped
work on Transformable instances
split out Context and Contextual into a separate module
D.Core.Envelope: Contextual-ize
work on Contextual-izing Juxtapose (one missing method)
Enveloped QDiagram
implement Juxtaposable (b -> a) instance
Merge remote-tracking branch 'origin/fixpoint' into gsoc

Conflicts:
	src/Diagrams/Core/Types.hs
Revert "wip"

This reverts commit a7029382e7837b5cf442716dc2e7af40cc59d5e6.

Conflicts:
	src/Diagrams/Core/Types.hs
Move Context back to Core/Types.hs

This is needed because Context depends on Environment which in turn
depends on RTree. I'm not really sure how to fix this cleanly,
especially because Contextual was originally factored out to make
contextual envelopes possible.

Perhaps RTree+Summary needs to be factored out as well? I'll leave this
undecided for now.
Degeneralize Annotation to cut down on the number of type parameters.

It's not obvious to me if Annotation was intended to be polymorphic. If
this ends up breaking anything, it can be reverted but then an extra
annotation needs to be added to contexts. This will probably not be an
issue either way if Contextual is fixed as per the previous commit's
comment.
Fix static errors and make the file compile (mostly)