v1.3.58

• Add bash-style built-in variables: $_, $-, $!, $OLDPWD (+ cd -), $USER, $HOSTNAME, $SHELL, $RANDOM, $SECONDS, and $POSHPID (posh's name for bash's $BASHPID). $PWD is now seeded at startup, not just after the first cd.
• Fix TAB completion never offering $RANDOM, $SECONDS, or $POSHPID, since those are computed on the fly rather than stored.