Renamed OpAssign{1, 2}.
Fixed bytecode for break in opasgn value.

The following code was not compiling:

  while a
    b[x] ||=
      (
        break if c
        d
      )
  end
Use pop_many instead of many pops.
Removed wrapping Tuple.
Added keywords support for definitions.
Bumped version to 2.2.0.