semantic: handle Union in ensureResolved
rt: Added aa.v, implemented RedBlackTree validation
rt: Implemented aa lookup and RBT tree-rotation
rt: Implement aa insertion
rt: change NIL nodes to null
rt: Implemented AA deletion
rt: Fix all the segfaults (aa)
rt: Rename KeyNode to TreeNode (aa)
rt: aa: WIP broken as hell
rt: aa: WIP
rt: AAs fully implemented