CHUI-778 (Saving preferences updates text in all open message panels in...

CHUI-778 (Saving preferences updates text in all open message panels in conversation floater to show as old messages) Problem was that closing the preferences floater was always acting as if the conversation transcripts/log files path had changed. If the path did not change then the user's conversations would be cleared and re-loaded as if they were part of the user's history (causing text to be grey). Solution: Now keep track of when the path was changed and only load up the transcripts/log upon change.