support attribute localization

[jdlrobson]

added data-localize-msg to jquery.localize -> allows for valid html markup,
provides a method to circumvent ie issues mentioned with and <html:msg key=""/>
added data-option-msg to jquery.localize -> provides a resolution to the issue
where jquery.localize cannot .find the msg within the elements
added to the jquery.localize embedded documentation

[jdlrobson]

OK, so I took a look at this and I'm not so keen on it.
Although I think html validation is useful to capture mistakes in markup I'm not sure what it wins us at the current time since this does not end up on the web (if it's just being able to run code through the validator then this could be achieved via replacing msg tags with span tags for example)

I would prefer a name convention data-msg for text and a generic data-msg-attributename if we were to go down this route - A comment tag may be a better way to go if the objections are with messages

Mostly I'm concerned about where jquery.localize come from? There is no license on it and it would be better for the change to be made upstream in that library. I'd hate us to run our own custom fork of it if it is still being maintained and not pick up any future updates.

[yuvipanda]

jquery.localize came from mediawiki's resources/jquery/jquery.localize.js, written mostly by Krinkle and Trevor (with contribs by brion and werdna). And +1 on not forking it.

[yuvipanda]

Closing pull req, since we don't want to fork from upstream.

[jdlrobson]

Here is the library:

https://gerrit.wikimedia.org/r/gitweb?p=mediawiki/core.git;a=blob;f=resources/jquery/jquery.localize.js;h=27cae292bf69a88b92e1d444d7f7784a789c090f;hb=HEAD

We should start conversations / submit pull requests for

• broken option tags
• html validation
• localising placeholder attribute
• getting html out of a msg tag in the html rather than having to resort to javascript