2008-12-15 Wakaba
* HTML.pm ($HTMLDatetimeAttrChecker): Removed.
($GetDateTimeAttrChecker): Added.
($GetHTMLFloatingPointNumberAttrChecker): Set |number_value| for
later use.
(ins/@datetime, del/@datetime): Changed to use newer definitin of
"global date and time string".
(input's date- and time-related, and type=number and type=range
control types): Implemented value="", min="", and max="".
2008-12-13 Wakaba
* HTML.pm: Implemented