Routines to manage the FuzzyDate Class. There is also an extension to the 
 ActiveRecord::Base class to provide an 'acts_as_fuzzy_date' class method.

 Historical dates are often incomplete or approximate and this class allows 
 such dates to be worked with and stored on a database.

 construct a new object with FuzzyDate.new( year,month,day,wday,circa)
    year:   optional..is the year number 0 .. big as you like, -ve for BCE
    month:  optional.. is month number 1..12, or nil
    day:    optional.. is day number 1-31 or nil
    wday:   optional.. day of the week - 0=Sunday .. 6=Saturday
    circa:  true = daye is approx, or nil/false

    note that if you supply the weekday and a year/month/day the system will
    use your weekday as supplied even if this does not actually correspond
    in reality to the date supplied.

  construct a new object with FuzzyDate.parse("date_string")
    date_string = eg: "tuesday"
                      "12 nov 1012"
                      "circa 412 bc"

  Use in a database table by storing in an integer field of a format large
  enough to hold the digits of your maximum year + 8. Eg. a BIGNUM field
  stores 19 useful characters allowing the year to go to 99,999,999,999.
  ie 99 billion years.

  Use with an ActiveRecord class ..

      require 'fuzzy_date'

      class HistoricalPerson < ActiveRecord::Base
          acts_as_fuzzy_date : birth_date, death_date
      end

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