Fixes and improvements to interwiki transclusion:

• allow interwiki {{subst:...}} using action=raw fetches
• Allowed non-MSIE browsers to access action=raw via the article alias. This is necessary to allow action=raw transclusion, since the only known URL is the article path, not the script path.
• Specify a user agent in wfGetHttp() fetches, when using curl.
• Added transcache table to tables.sql, it was in the updater but not there for some reason.
• Fixed transcache expiry, added option
• Allow interwiki transclusion outside the template namespace using leading colon syntax. Syntax is counterintuitive at times, e.g. to subst the wikipedia main page you would use {{subst::Wikipedia:Main_Page}} not {{subst:Wikipedia::Main_Page}}.