Added ability to use "@" symbol in command named in the inittab file. This
treats commands as literal and does not launch a shell to interpret them.
Updated inittab manual page to include overview of symbols which trigger
a shell interpretor and how to disable them using the @ symbol.
This information can be read by the "runlevel" command as well as "halt"
and "reboot". Having the information logged in /var/run/runlevel as
well as the utmp file means systems without utmp (like those running
the musl C library) can still check the current runlevel. This is
useful when running halt/reboot as these programs want to check the
runlevel.
Updated the changelog, and manual pages for halt and runlevel.
