Script Summary: This script adds a field after the existing date fields where you can paste a date and it will try to parse it.
This currently works in Opera 12, Firefox 22 and Chrome. I haven't tried any other browsers.
* Numeric dates in the form DD MM (YY)YY, MM DD (YY)YY or (YY)YY MM DD. Day and month are optional. It's not fussy about the separators.
* Numeric dates with the month written in roman numerals (e.g. 07.VIII.2009).
* Dates with the full or abbreviated month name (e.g. February 15 2001, 8 Mar 99) including Spanish months in the form "DD de month de YYYY".
* Ordinal numbers in dates with the month name (e.g. 1st May 2010).
* Thai year numbering (e.g. 07.08.2552), Japanese eras (e.g. 平成21年12月30日) and Taiwanese year numbering (e.g. 民國98年08月07日).
* Month names/abbreviations in many languages. If you come across some it doesn't support, give me a link to the site where you found it and I'll see what I can do.
* Dates with no separators (e.g. 20090807; 07082009; 08072009).
* Any other calendars.
None right now.
2014-04-12: Support letters representing years on older Japanese releases (e.g. O-7-5 for 1987-07-05) and 元年 for the first year of a Japanese era (e.g. 平成元年 for 平成1年).
2014-02-22: More fixes from bitmap so that it works when changing entity types in the relationship editor and when trying to type in the individual year/month/day fields.
2014-02-21: bitmap fixed it so it works again Chrome and newer versions of Firefox. \o/
2014-02-18: Tiny update to stop it from loading twice in the release editor.
2013-02-17: Should now understand months with accents in the name (e.g. "März"), Spanish-style dates in the form "DD de month de YYYY" and it no longer thinks mayo is April.
2013-02-08 v2: Should now really work in the relationship editor. Now understands fullwidth digits (thanks jesus2099), Japanese eras, Taiwanese year numbers and ordinal numbers.
2013-02-08: Should now work in the relationship editor.
2012-09-19: CJK/Korean dates with incomplete years (e.g. 08年03月02日) are no longer considered ambiguous. Links for selecting multiple possibilities now use a hand cursor. Added missing French months. Added https support.
2012-04-14: Fixes to the regexes which should mean better matching in Opera. Thanks Bitmap!
2012-01-06 uploaded 2012-04-14: This version apparently fixes the bizarre suggestions.
2012-01-05: Fix silly mistakes in regexes to allow days greater than 12 when there's a month name. Added Spanish months to the list of month names.
2012-01-04: Add support for month names, numeric dates with the month in roman numerals and Thai year numbers.
2011-12-24 v2: Fix display in the release editor
2011-12-24: Fix handling of multiple possibilities
2011-12-23: Original version