Active file descriptor watches and active timers are now automatically...

Active file descriptor watches and active timers are now automatically transferred to the component declaring a custom event loop.

[INTERPRETER]
* BUG: Active file descriptor watches and active timers are now automatically transferred to the component declaring a custom event loop. Consequently, a process started before the declaration of the event loop will have its termination signal correctly catched.
* NEW: Use waitpid() instead of wait4().

[GB.GTK]
* BUG: Declare the event loop hook last so that active file descriptor watches and active transfer are automatically transferred.

[GB.GTK3]
* BUG: Declare the event loop hook last so that active file descriptor watches and active transfer are automatically transferred.

[GB.QT4]
* BUG: Declare the event loop hook last so that active file descriptor watches and active transfer are automatically transferred.

[GB.QT5]
* BUG: Declare the event loop hook last so that active file descriptor watches and active transfer are automatically transferred.