Changes for version 0.10
- Tuned SIGCHLD handling again (thanks to the ASF for their merciless "ab").
- Added support for DEFAULT, IGNORE and undef child signal handlers.
- _read_child_data(): Read more than one data chunk per call but not too many.
- Execute child_data_hook in separate process unless data_hook_in_main is true.
- t/02-data_hook.t needs data_hook_in_main => 1.
- Parallel::MPM::Prefork - A simple non-threaded, non-OO, pre-forking, self-regulating, multi-purpose multi-processing module. Period.