Changes for version 1.02
- make extra sanity checks configurable.
- abort, not croak, when checks fail, as error is in XS code.
- improve portability to non-gcc-compatible compilers, where perl falls back to a slow workaround that requires dTHX.
- do not start first thread at module load, this is not required and potentially harmful with the current model.
make coro threads on multiple cores with specially supported modules