FIXED: Provide error messages for, as yet, not-supported function
expansion for meta-arguments.
Updated clib
DOC: removed no-longer-relevant section on SIGSEGV handling.
MODIFIED: Catch most signals and call PL_exit_hook() functions before
killing ourselves with the same signal.  Extended the set of `crash'
signals that cause the system to print a stack-trace.
Updated clib
Avoid kill() on systems that do not have it.
use foldl/4
use foldl/5
FIXED: nb_rb_get_node/3: avoid arg/3 on ''.  Jacco van Ossenbruggen