templatefilters: add filter to convert date to local date (issue1674)

Issue1674 suggests the localdate filter be applied as default to log,
but this patch only introduces the filter, not the changed default
behaviour.

mercurial/help.py

@@ -341,6 +341,7 b' PYTHONPATH::'
     - hgdate: Date. Returns the date as a pair of numbers:
           "1157407993 25200" (Unix timestamp, timezone offset).
     - isodate: Date. Returns the date in ISO 8601 format.
+    - localdate: Date. Converts a date to local date.
     - obfuscate: Any text. Returns the input text rendered as a
           sequence of XML entities.
     - person: Any text. Returns the text before an email address.

mercurial/templatefilters.py

@@ -192,6 +192,7 b' filters = {'
     "isodatesec": lambda x: util.datestr(x, '%Y-%m-%d %H:%M:%S %1%2'),
     "json": json,
     "jsonescape": jsonescape,
+    "localdate": lambda x: (x[0], util.makedate()[1]),
     "nonempty": nonempty,
     "obfuscate": obfuscate,
     "permissions": permissions,