Report filenames with disallowed characters as suggested by Mika Eloranta (see issue671)

hgweb: Quote filenames when downloading raw files.

hgweb: Pass only filename instead of full path when downloading raw files. Before this patch "filename=foo/bar" was sent and e.g. Firefox offered to save the file as "foo-bar" instead of just "bar".

merge with crew

Make annotae/grep print short dates with -q/--quiet. Move shortdate() from templatefilters to util to avoid code duplication.

Add hg grep -d/--date to list the commit date of matched revisions. Suggested by Greg Lindahl

util: always define a dummy lookup_reg()