LocalTimezone and FixedOffset are no longer useful

[sampsyo]

The icalendar.prop provides a couple of subclasses of datetime.tzinfo called LocalTimezone and FixedOffset. These made sense with the "old" version of this module, but now, since all tzinfo arguments must come from pytz, these classes no longer work. Using them causes an error like this:

...
  event.add('dtstart', date)
File ".../icalendar/cal.py", line 296, in add
  tzid = value.tzinfo.zone
AttributeError: 'LocalTimezone' object has no attribute 'zone'

So these classes should probably either be removed or updated to inherit from the pytz class.

[thet]

@sampsyo i guess, i gonna remove the code.
did you somehow rely on the old timezone behavior?
related: #44

[sampsyo]

I agree—remove the code. No, I don't have anything that depends on it; I was just writing a new app and got confused when they didn't work.