simplify

Graph

(0) +60 +100 tip
Added a link from the original node to any corresponding new node.
Added produces_result to some Invoke nodes, returns_value to some Subprogram
Added Slice support, along with Slice participation in AugAssign node groups.
Added Raise, fixed TryExcept for empty handler specifications.
Added UnaryAdd, UnarySub, Invert.
Added From and Import.
Added AugAssign, introduced index attributes to LoadTemp/StoreTemp/ReleaseTemp.
Added Global, And, Or, Not and made minor fixes.
A simplified AST processor.
(0) +60 +100 tip