Implement "simple scan" functionality

[edermi]

The idea is to have a scan command that does a scan using standard options from the current system.

Often the interest of the user lies at quickly identifying systems and a few ports, e.g. for debugging purposes (is the system alive, is a port open, is it reachable etc.).

Parameters that may be passed via command line:

• scantype (TCP, UDP)
• targets (CIDR, file)
• ports (list, range, "topN")
• number of workers
• output filename

Many other options aren't required (e.g. network stuff, TLS etc) or should be disabled because they increase complexity and exceed the scope of a "quick and simple" scan (e.g. other data sources or event sinks).

[edermi]

Implemented on develop