Simplify WeeklySchedule interfaces
Simplify WeeklySchedule interfaces

Constructor now takes one of the many possible representations
to the constructor, and it will try to do the right thing:

  ['M', 'Tu', 'Fri']   list of day names
  "['M', 'Tu', 'Fri']" string representation of a list of day names
  "M, Tu, Fri"         string of comma-separated day names
  "20"                 string of an integer 0-127
  20                   integer 0-127 representation

Raises TypeError if 'weekdays' cannot be parsed.

More consistent API:
    from_byte & to_byte
    from_list & to_list
    from_words & to_words

More doctest coverage.

thomashamlin/python-days-and-schedules