MFC revisions 257795,257817,257819,257937-257938,258264-258265,258267,

MFC revisions 257795,257817,257819,257937-257938,258264-258265,258267,
258854,259113,259427 (11 revisions; summarized below).
r257795: Replace pkg-tools with pkgng
r257817: Fix cosmetic typos
r257819: Use `pkg -vv' to obtain ABI
r257937: Unbreak the installer
r257938: Remove the env(1) but keep the var
r258264: Kick an unused orphan to the curb ;)
r258265: Improve debugging with f_eval_catch()
r258267: Fix package installation from physical media such as DVD
r258854: Fix PKG_ABI detection after pkg-1.2
r259113: Fix failed attempt to send pkg(8) stderr to /dev/null
r259427: Export 'REPOS_DIR' when selected source medium is cdrom

MFC after:	3 days

git-svn-id: svn://svn.freebsd.org/base/stable/9@267683 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f