Allow to_date() and to_timestamp() to accept localized names

Hello,

Going through the current items in the wiki's todo list, I have been
looking into: "Allow to_date () and to_timestamp () to accept
localized month names".

It seems to me that the code is almost there, so I would like to know
if something like the attached patch would be a reasonable way to go.

Regards,

Juan José Santamaría Flecha