minor: add O_NONBLOCK to open() flags

minor: add O_NONBLOCK to open() flags
(paranoia for error behavior in face of mandatory locking (non-POSIX)
(man fcntl(2))
simplify bsock_bindresvport_random_port()

simplify bsock_bindresvport_random_port()
documentation already states that code is not cryptographically secure
(even if it does use /dev/urandom)
minor: hyperlink updates in doc
proxyexec: improve cmd string expansion behavior

improve command string expansion behavior when proxyexec is user shell
version 0.08 - proxyexec enhancements

improve command string expansion behavior when proxyexec is user shell