Defined Meaning Namespace + lang/user global fixes

When a preferred language is not found in wgLang, the preferred language
is searched at wgUser first, before defaulting to English, and then any
other language.

Patch 2:
Restructured two database API functions to display both the expression and
definition to the user language preference, if available. removed a @todo.

Patch 3:
Special page Suggest now outputs in the preferred language in some languages
like Min Nan and German. Using $wgUser global instead of $wgLang seems to
be preferred, since this fixed the Min Nan and German problem of always
seeing English.

Patch 4:
created more lang/user global safety net, so more data will be displayed
under the user's language preference.

Patch 5:
an error at WikiDataAPI, fixed.

Patch 6:
additional note on the lang/user global issue.

Patch 7:
additional lang/user safety nets created.

I think I have covered most of them. Kindly check and merge when there are
no more issues and/or suggestions. Thanks!

Change-Id: Id7e6d73eab24285797569dbefd904e5424543452
Merge "Defined Meaning Namespace + lang/user global fixes"