add a new template function 'hgdate'
'hgdate' turns a date into a cset timestamp as printed by 'hg export'
# repo.py - repository base classes for mercurial## Copyright 2005 Matt Mackall <mpm@selenic.com>## This software may be used and distributed according to the terms# of the GNU General Public License, incorporated herein by reference.class RepoError(Exception): pass