bpo-33907: Rename an IDLE module and class. (GH-7807)

Improve consistency and appearance. Module idlelib.calltips is now calltip.
Class idlelib.calltip_w.CallTip is now Calltip.
diff --git a/Lib/idlelib/run.py b/Lib/idlelib/run.py
index 176fe3d..6fa373f 100644
--- a/Lib/idlelib/run.py
+++ b/Lib/idlelib/run.py
@@ -11,7 +11,7 @@
 import tkinter  # Tcl, deletions, messagebox if startup fails
 
 from idlelib import autocomplete  # AutoComplete, fetch_encodings
-from idlelib import calltips  # CallTips
+from idlelib import calltip  # Calltip
 from idlelib import debugger_r  # start_debugger
 from idlelib import debugobj_r  # remote_object_tree_item
 from idlelib import iomenu  # encoding
@@ -462,7 +462,7 @@
     def __init__(self, rpchandler):
         self.rpchandler = rpchandler
         self.locals = __main__.__dict__
-        self.calltip = calltips.CallTips()
+        self.calltip = calltip.Calltip()
         self.autocomplete = autocomplete.AutoComplete()
 
     def runcode(self, code):