Refactored handles internal allocation scheme

* C handles are allocated in tp_new
* C handles are initialized on __init__
* A Flag is used to determine if a subclass didn't call __init__ and
  raise RuntimeError
* C handles are freed on tp_dealloc, never earlier
* Removed FSEvent.start and moved functionality to __init__

All this should make the interaction between the C and Python objects
easier.
Adapted to FSEvent API changes in test
Removed FSEvent basetype test

The handle is started in __init__ now
Fixed bogus class name for FSPoll basetype test
Removed bogus line
Fixed returning bogus value from property