The goroutine running the monitor isn't actually closed. This PR updates
the API to allow that Goroutine to properly block program exit. This can
be leveraged as we continue to make the configuration non-global.
This updates MakeMonitor() to take the channel size as a parameter,
instead of reading it from the global `config` object. Unfortunately,
the caller of MakeMonitor() doesn't actually have access to the global,
since it's in a different package (bin vs the root package). Luckily,
there doesn't appear to be a reason to have a buffer in this channel.
This updates the caller to pass a hardcoded size of 1.
Move ZGrab2's main function to a library, and call it in cmd/zgrab2
after importing all of our modules. Consumes of ZGrab2 as a library can
use the same approach to provide custom sets of modules, without having
to hack the build system or reimplement main.
https://github.com/zmap/zgrab2/pull/224
