When able, cycle lines in .dialog files
When able, cycle lines in .dialog files

Attempt to use a different line each time a .dialog file is invoked.

====  Tech Notes ====
MustacheDialogRenderer:
  - Keep a running list of recently spoken lines (up to 3)
  - If there's more than one line in a dialog file, don't repeat lines
  - Pop lines from the list when full or when dialog file is running low

====  Documentation Notes ====
Consider encouraging skill authors to include multi-line .dialog files,
as this will help to give Mycroft a more natural feel

Dark5ide/mycroft-core,MycroftAI/mycroft-core,Dark5ide/mycroft-core,forslund/mycroft-core,forslund/mycroft-core,MycroftAI/mycroft-core