Prove Forall3_app.
Decider for empty listsets.
Misc lemmas on option.
Repeat function on streams.
Make collection tactics work with guards.
More checks in frontend.
Rename wrongly named function maybe_CCall_redex into maybe_ECall_redex.
Hack to support events and random execution path in interpreter.
Weakening lemmas for refinements.
Remove lemmas for alloc steps with specific fresh index.
Towards completeness of the interpreter.