dpkg-buildpackage: add a new -R option and allow parameters in -r

dpkg-buildpackage: add a new -R option and allow parameters in -r

* scripts/dpkg-buildpackage.pl: Add a new -R option to be able to replace
"debian/rules" by something else. The replacement command can contain
parameters (and thus spaces). Fix -r option to also accept parameters.
* man/dpkg-buildpackage.1: Document the new option and the changed
behaviour of -r.