Add a link to the varnishlog man page and the logging chapter in the tutorial

remove -i and -I, add -m and describe it. Simplify the docs. The user only needs to care about -m, really

I'm not sure if we should go into more detail about how the whole thing works

Fixes #1062

of maintaining magic hex-bit values that must match.

Fixes #1042

Use a mark&mark strategy to test all obj.* bans even if there are
req.* bans in the way.

started fixing that, and then I fixed another couple of nits and polished
the naming a bit and ...

Well, you know how it is.

Changed the backend matching function to take a call-back function
to eliminate the need for the memory which got leaked.

This meant that backend.list could also use it, if only the parsing
code accepted a blank input.

So I rewrote the parsing code to also allow empty names, so you can:
	backend.list (:80)
	backend.list (192.168)
etc.

And then I added a summary report of the probing, if it is happening,
and explicitly say that no probing is happening if it isn't.