parse_args(
body) ->args
Parse a URL-encoded form body into a key-value table
Parses an application/x-www-form-urlencoded body. + signs in values
are restored to spaces before URL-decoding. Values come back raw: the
caller escapes one at output, with html_escape for HTML. Returns an
empty table for non-string or empty input. Key-value pairs missing the
= separator are silently skipped.