- Add Horde_Date_Parser_Result for holding complex results from

- Add Horde_Date_Parser_Result for holding complex results from
  Horde_Date_Parser#parse()

- Replace the 'guess' option with a generic 'return' option that allows you to
  pick a Horde_Date, Horde_Date_Span, or Horde_Date_Parser_Result

- Move the guess() function to the Horde_Date_Parser_Result object (maybe it
  should actually be on the span itself?)

- Horde_Date_Parser_Result can return the tagged or untagged text from the
  original string.