Make phpsploit script usable in shellbangs

Shellbangs like "!/usr/bin/env phpsploit"
are now working in scripts (implicitly inserting '--source' option
in arguments when it is appropriate.

Other changes:
    ui.interface.interactive (bool):
        This var now informs core if we run in interactive mode
Output at interface.init() are now debug messages

It makes parsing of a single phpsploit command result
easily parseable through a shell script without worying
with eventual interface init actions that can write some
information messages
BugFix: @isolate_io_context had readline as dep!

Now readline is handler, but as optional dependency,
just like the phpsploit framework flavour.