ui: add the possiblity to get a date config field

Add the method configdate to read a date from configuration. It uses the
util.rawparsedate refactored earlier to support all standard date formats.

mercurial/ui.py

@@ -598,6 +598,19 b' class ui(object):'
         return self.configwith(config.parselist, section, name, default or [],
                                'list', untrusted)
 
+    def configdate(self, section, name, default=None, untrusted=False):
+        """parse a configuration element as a tuple of ints
+
+        >>> u = ui(); s = 'foo'
+        >>> u.setconfig(s, 'date', '0 0')
+        >>> u.configdate(s, 'date')
+        (0, 0)
+        """
+        if self.config(section, name, default, untrusted):
+            return self.configwith(util.parsedate, section, name, default,
+                                   'date', untrusted)
+        return default
+
     def hasconfig(self, section, name, untrusted=False):
         return self._data(untrusted).hasitem(section, name)