yet again, this time due to the space having been removed from local $IFS.
This is fixed now, but there's still a bug remaining, namely that completion
does not work correctly if dirs or subdirs of entries in $CDPATH contain
embedded spaces
_longopt(): install completion for {mk,rm}dir as -o filenames, not dirnames
_killall() now calls _signals()
new _kill() function for kill completion
_killall() now only completes on signals if parameter starts with a '-'.
It would previously return process names AND signals for a blank parameter.