Add argument path matching support. Bug #11066.

Add argument path matching support.  Bug #11066.

2007-09-20  Ryan Lortie  <desrt@desrt.ca>

        * dbus/signals.c (struct DBusMatchRule, bus_match_rule_new,
        bus_match_rule_set_arg, bus_match_rule_parse_arg_match,
        match_rule_matches): Add support for parsing and matching on
        arg0path='/some/path' type rules.

        * dbus/signals.h (bus_match_rule_set_arg): change to take const
        DBusString instead of const char * for the string to match against.

        * dbus/dbus-bus.c: add a quick note to dbus_bus_add_match
        documentation about the path matching.

        * doc/dbus-specification.xml: add a more detailed description of the
        changes here.