Improve removing arguments from documentation

Examples of issues where user used arguments which should not be present in 
documentation, but actually were present: #1699 (cpu_load_percent: 
shutdown_event), #1700 (weather: key, after_update, shutdown_event).

powerline/lib/threaded.py

@@ -158,17 +158,16 @@ class ThreadedSegment(Segment, MultiRunnedThread):
 	def additional_args(self):
 		return (('interval', self.interval),)
 
+	_omitted_args = {
+		'render': (0,),
+		'set_state': ('shutdown_event',),
+	}
+
 	def omitted_args(self, name, method):
+		ret = self._omitted_args.get(name, ())
 		if isinstance(getattr(self, name, None), MethodType):
-			omitted_indexes = (0,)
-		else:
-			omitted_indexes = ()
-		if name.startswith('render'):
-			if omitted_indexes:
-				omitted_indexes += (1,)
-			else:
-				omitted_indexes = (0,)
-		return omitted_indexes
+			ret = tuple((i + 1 if isinstance(i, int) else i for i in ret))
+		return ret
 
 
 class KwThreadedSegment(ThreadedSegment):
@@ -255,3 +254,9 @@ class KwThreadedSegment(ThreadedSegment):
 	@staticmethod
 	def render_one(update_state, **kwargs):
 		return update_state
+
+	_omitted_args = {
+		'render': ('update_value', 'key', 'after_update'),
+		'set_state': ('shutdown_event',),
+		'render_one': (0,),
+	}

powerline/lint/inspect.py

@@ -39,7 +39,9 @@ def getconfigargspec(obj):
 		for i, arg in enumerate(reversed(argspec.args)):
 			if (
 				largs - (i + 1) in omitted_args
+				or arg in omitted_args
 				or arg == 'pl'
+				or arg == 'self'
 				or (arg == 'create_watcher' and requires_filesystem_watcher)
 				or (arg == 'segment_info' and requires_segment_info)
 			):

powerline/segments/common/env.py

@@ -44,7 +44,7 @@ class CwdSegment(Segment):
 
 	def omitted_args(self, name, method):
 		if method is self.get_shortened_path:
-			return (0, 1, 2)
+			return ()
 		else:
 			return super(CwdSegment, self).omitted_args(name, method)
 

powerline/segments/common/players.py

@@ -62,7 +62,7 @@ class PlayerSegment(Segment):
 		yield 'get_player_status', self.get_player_status
 
 	def omitted_args(self, name, method):
-		return (0,)
+		return ()
 
 
 _common_args = '''