This makes the interwiki map available to Lua modules. The code is
based on the API interwiki map code in core (the appendInterwikiMap
method of includes/api/ApiQuerySiteInfo.php.) Everything that the
API includes is added, apart from iw_api and iw_wikiid, which I
couldn't think of a use for from Lua modules.
Accessing the interwiki map would be useful for modules like
enwiki's Module:InterwikiTable,[1] as it would stop module writers
having to duplicate the data.
[1] https://en.wikipedia.org/wiki/Module:InterwikiTable
Change-Id: Ie8ad2582aaf5e422824f7da51714a347bb4041d1
The PHP call that makes mw.site.namespaces work case-insensitively
doesn't handle non-standard spaces/underscores. So standardize them
before the call.
Bug: 56216
Change-Id: I4758478b126858fb581614f64eb15472f42fef51