Hover/cursor placement only works on final joint theorem

[ionathanch]

joint
  theorem zero : True
  theorem one : True
  theorem two : True
by all_goals constructor

Placing the cursor at zero or one doesn't show its type in the infoview, but placing it at two does. Similarly, hovering over zero or one only shows the doc comment for the joint macro, but hovering over two shows its type.

[ionathanch]

At the very end of expandJoint, we return all of the new definitions in an array:
return mkNullNode (#[jointDef] ++ nthThms).
It seems that whichever is the last definition in nthThms will be hoverable...