Updated error message in MGT_Child_Cli_Fail to indicate that we
actually have sent the kill signal to the child process.

A new jail level, JAIL_MASTER_KILL, is introduced. The mgt process
takes this level before killing the child process.

Fixes: #2010

A new function, kill_child() is introduced, so that kill() is only
called from this function. This is a preparation of fixing the jail
implementation.

There seems to be an error in the varnish jail design, which makes the
mgt process uable to kill the child process. To confirm this, add some
error checking to the relevant code.

Related to: #2010

Spotted by:	gquintar

impatience to make -t argument controlling

doc fixes #2107

This test wasn't working as it was supposed to, and would cause the
forward links graph building of log transactions to fail. The fail was
soft, as the reverse mapping still succeeded creating the right
mapping.

Depending on when the local thread log buffer was flushed, the problem
would show as spurious "duplicate link" log records to be inserted.

Fixes: #1830

Fixes #2105. Minor test cleanups while here.

Let's see how many grammar/spelling fixes are going to follow :/

More to come.

Fixes #2017.

This reverts commit 6da0cfda.

That was a stupid commit, the malloc failure is already handled

Spotted by: @scn

Since a78efad8 the argument name and default
value are separated from the argument spec by a \1, so we need to stop
there.

Fixes: #2094
Fixes: #2096

makes a valid H1 request header.

One submitted by github::bobmshannon.