return.value and return =

[edemaine]

I used what I learned from writing #359 to fix #361 and this time keep things particularly clean.

Extra features:

• Simpler global ref resolution from break used as value for detecting broken loops, simpler global ref resolution #359 (necessary if return.value is used within a loop, and ret is used only outside)
• Add parent pointers and findAncestor helper
• Remove parent pointers during prune
• CLI error handling when AST fails to JSON.stringify (helped figure out that I need the previous)
• getIndent helper extracted from insertReturn
• gatherRecursive gains a skipPredicate (not strictly necessary but convenient)
• gatherRecursiveWithinFunction to search just within this function (probably would simplify autoVar code)
• isFunction helper

[STRd6]

Just need to update the return value when matching skipPredicate to [].