following promotion of DRTVWR-554

following promotion of DRTVWR-552

also cleaned up some xui warnings

token input is now handled and message formatting is improved.
Added beginnings of support for saving slmfa_hash value client side.

We now present MFA errors to the user during login and prompt them for
an authentication token.

# Conflicts:
#	indra/newview/app_settings/settings.xml

# Conflicts:
#	indra/newview/VIEWER_VERSION.txt

# Conflicts:
#	README.md

following promotion of DRTVWR-545

by Callum

by Callum

Fix for SL-16208 Introduce a canonical_repo tag into the autobuild.xml file for new 3p repos - no new code introduced in this pass