Signed-off-by: Rainer Gerhards <rgerhards@adiscon.com>

Added $PrivDropToGroup, $PrivDropToUser, $PrivDropToGroupID,
$PrivDropToUserID config directives to enable dropping privileges.
This is an effort to provide a security enhancement. For the limits of this
approach, see http://wiki.rsyslog.com/index.php/Security

... which permits to drop root privileges. This is not a completely
secure way of dropping permissions, e.g. the group permissions need
to be dropped, too. Also, there are several vulnerability Windows (see
code comments). Finally, at least the imklog module on linux does
not work when privileges are dropped. This code may still be a
valuable addition, and so I have created an experimental branch so
that people can check it out.

Conflicts:

	ChangeLog
	configure.ac
	doc/manual.html
	doc/property_replacer.html

Conflicts:

	ChangeLog
	doc/manual.html

This is intended for debugging and considered worth preserving.
However, it has not (yet) been added to the build diag tools
as it is not considered important enough.

...which enables to configure HUP to be either a full restart
or "just" a leightweight way to close open files

Conflicts:

	ChangeLog
	configure.ac

Conflicts:

	ChangeLog