core.pyx: update __all__

gevent/core.pyx

@@ -21,8 +21,7 @@ However it is currently more up to date with regard to libevent API.
 .. _pyevent: http://code.google.com/p/pyevent/
 """
 
-__all__ = ['event', 'read_event', 'write_event', 'timer', 'signal', 'active_event',
-           'init', 'dispatch', 'loop', 'get_version', 'get_method', 'get_header_version']
+__all__ = ['event_base', 'evdns_base', 'event', 'get_version', 'get_header_version']
 # note, that .pxi files append stuff to __all__
 
 import sys