Anti-dependencies rewrite

• Re-write anti-dependencies properly using full dataflow analysis, incorporating new collection information.
• Use anti-dependencies properly in code generation.
  • TODO: figure out how anti-dependencies gets incorporated into GCM.
• Track which nodes mutate collections in collection analysis.
• Skeleton for materialize clones pass.
• Test for anti-dependencies (passes) and for materializing clones (fails).
• Fix pass.rs not clearing a bunch of analyses.