pretty-printing of ASM ClassNode, MethodNodes, and instructions as well
SI-6720 fixed in GenBCode
SI-6759 fixed in GenBCode
GenBCode: pipelined class building and class writing

Traversing a ClassDef to build an ASM ClassNode requires typer and
therefore must run single-threaded.

However, bytecode transformers that manipulate ClassNodes
don't need typer and thus can run in parallel.

Two other activities that don't depend on typer either are:
  - encoding ClassNodes into the byte array representation of a classfile
  - writing classfiles to disk

The activities above (building ClassNodes, encoding, disk writing)
are performed in different threads (for now, "encoding" is only lightly
loaded, but in the future certain optimizations will run there).
GenBCode turned on by default