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.
it closes (and leaves closed) the named pipe /run/initctl. This
can be used to make sure init does not have any files open. However,
it also means we cannot switch run levels or bring down the system.
The pipe can be re-opened by sending init the SIGUSR1 signal.
Updated the man pages for initctl and init to include this information.
