[dvd::rip] rules for subtitle time shift are too strict

[Jon Malachowski <coolsnowmen@xxxxxxxxx>]

the extsub option to transcode supports negative time shifts but the 
dvd::rip gui rules prevent it
"extsub=0:-30:-2000:0:0:128:255:2:1" is perfectly valid.

simply, this fixes it for me. (this diff -u done on dvdrip 5.8.8)


--- Video/DVDRip/GUI/Project/Subtitle.pm.old    2008-07-17 
13:53:30.000000000 -0400
+++ Video/DVDRip/GUI/Project/Subtitle.pm.new    2008-07-17 
13:52:32.000000000 -0400
@@ -278,7 +278,7 @@
            Gtk2::Ex::FormFactory::Entry->new(
                attr  => "subtitle.tc_time_shift",
                width => 50,
-                rules => "positive-integer",
+                rules => "integer",
            ),
            Gtk2::Ex::FormFactory::Label->new(
                label       => __ "ms",