AnonymousClassLoader overhaul

[Rémi Forax]

Hi all,
there are several changes, i would like to apply on AnonymousClassLoader:
- make a clean separation between the classloader,  the constant pool 
parser and
  the patch array.
- avoid to iterate over all constant pool entries when applying a patch
  on the same base class (remove indexOf() in makePatchArray)
- try to make it thread safe
- allocate the bytecode array using ByteBuffer instead of byte[]
   (not sure it's possible).
- generify it (Class => Class<?>)

i will try to submit a patch soon.

Rémi