Uninstalls signal handlers, resets terminal to normal operation, et cetera.
Parameters:
services - a set of INI_xflags denoting which subsystems are to
be shut down. This argument is almost always equal toINI_ALL. Certain operations may need to temporarily suspend a few BBS
subsystems, which is why this function allows a partial shutdown. However,
this is an exception and not the rule. Services will be shut down
only if they have been previously initialised by a corresponding call tomod_init().