TODO-eo2

- eo_composite_attach
   maybe check that the class of comp_obj is part of parent extensions

- Eo2_Call_Stack
   grow/shrink
   stack push and pop functions
   per thread stack

- Remove the memset in do_end? Waste of cpu...

- cleanup EO2_VERSION specific code in eo.c and eo_private.c

- Move the Op_Descs to be set using a function inside the class_constructor
   check if it works ASIS on windows
   if it does, do nothing

- Rediscuss the whole attribute cleanup thing. I'm not sure we want that as everything breaks if that isn't there. Embedded old gcc?

- function name from pointer
   dladdr backtrace ??

- Get rid of some of the EO2_VOID_FUNC_BODY?

- Add line number to errors (like in eo1...)

- A bit annoying that we don't get type checks on the callbacks, fix that? That's really dangerous!

- Get all the optimisations cedric has been doing to Eo1? I think that's where the children thing got lost...
    - Make sure all the improvements have been migrated...

- Fix all the FIXME