Level 1 intra-method optimiz: cancel out box-unbox pairs
Level 1 intra-method optimiz: compacting method-local vars

"Compacting" of non-param local-vars involves:
   - detecting gaps in the index sequence, followed by
   - re-numbering that shifts indexes to close the gaps.

As already hinted, "compacting" excludes parameters.
Also, a local-var that at least gets initialized won't be removed.
BCodeOpt: test dead-store elimination, part 1
BCodeOpt: test dead-store elimination, part 2
intra-method optimizations activated by default