Removing deprecated class/functions marked for deprecation in 3.0/3.1
Merge pull request #3433 from chillu/pulls/authenticate-backurl-master

Don't clear BackURL after MemberAuthenticator::authenticate()
Merge pull request #3425 from halkyon/removing_deprecated2

Removing deprecated class/functions marked for deprecation in 3.0/3.1
Merge branch 'master' of https://github.com/silverstripe/silverstripe-framework into pull-i18n