Use --help-interactive to get cmds from -cli

When building the man page, use the --help-interactive option to
bladeRF-cli to get the list of interactive commands.
Reformat bladeRF-cli help

Because of how man pages format things, it's easiest (maybe) to
use tabs and whatnot to designate indentation, etc, in the help
output.

This unfortunately makes some of the help output look relatively
crappy, but at least it is more consistent!  :-)

Additional fixes/tweaks will ensue.
Merge branch 'rtucker-issue211' into issue211
Initialized value for help-interactive option flag

Previously, I hadn't explicitly initialized the flag used to indicate
whether the --help-interactive command line option had been provided,
which would sometimes cause the --help-interactive output to be
displayed even when the option was not specified. In particular, when
help2man would execute the --version option, it would sometimes instead
get the --help-interactive output, which was obviously no good.