Refs #8140 Updated DataSelector with suggested changes.
Refs #9007 Swap interface to use new implementation.
Refs #9007 Add extra validation check on loaded file.

It is a common situation when using auto-loading that the loaded file could get deleted before being used.
I've added this check to automatically take care of this, and if re-loading fails, UserInputValidator will now output an appropriate error message.
Merge branch 'master', remote-tracking branch 'origin' into bugfix/9007_dataselector_missed_commit
Refs #9007 Use a better way of flagging a file problem.
Refs #9007 Update interfaces to use new validation mechanism.

This also removes redundant code that wouldn't be needed after this ticket.
Refs #9007 Remove dead code.
Merge remote-tracking branch 'origin/bugfix/9007_dataselector_missed_commit'