remove LOADNIL, not used anywhere

tested all examples and test cases
gettable as single op

parsed into 2 cases: hash[var] or hash["const"]
   (value (lick (msg ("hash") list (lick (value ("imm")))))
or (value (lick (msg ("hash") list (lick ("imm"))))

Still WIP

TODO: we really want fast arrays accesses, not hashes. Hashes are fine
as method call, but gettuple could be better jitted.
So rather change arr(x) => arr[x] and stay with hash at()?
This would be a step away from lua (h[] for hashes)
and a step nearer to perl (a[] for arrays)