Can be used to parse dates appearing in http response headers such
as Expires or Last-Modified. Automatically recognizes
most common formats. If the format is known, strptime
might be easier.
# NOT RUN {# Parse dates in many formatsparse_date("Sunday, 06-Nov-94 08:49:37 GMT")
parse_date("06 Nov 1994 08:49:37")
parse_date("20040911 +0200")
# }