Item11507: determine user preferences for the user being mailed. This allows us to present the mail in the language of choice for the user, rather than the default language.

git-svn-id: http://svn.foswiki.org/trunk@17615 0b4bb1d4-4e5a-0410-9cc4-b2b747904278
Item11507: need to be able to stomp the i18n object if the language changes mid-run.

git-svn-id: http://svn.foswiki.org/trunk@17616 0b4bb1d4-4e5a-0410-9cc4-b2b747904278