* does not use `errno` directly anymore, but instead returns the errno codes
as the return value (sometimes as negative numbers)
* change init error code to EINVAL, because that's what the other code uses.
* fix some gcc compile problems
* Adapt to changes in `mulle_allocator` and `mulle_aba`
* Remove dependency on `mulle_aba` for the pure library.
* Rename _free to _done.
* Merycful Release