Test harness: test all obfuscation levels

Some of the levels are inclusive and will actually overwrite any
changes by previous obfusction. Test them regardless.
Fix fib.lua non-deterministic outputs

Odd bug, not sure what the problem is but it gives different results
sometimes. Didn't look into it much, I was guessing something along
overflow so I lowered the input to 20 and it seems to work now.