Fix typos in comments, docs and test names (#15018)

* Fix typos in comments, docs and test names

* Update test_pyparse.py

account for change in string length

* Apply suggestion: splitable -> splittable

Co-Authored-By: Terry Jan Reedy <tjreedy@udel.edu>

* Apply suggestion: splitable -> splittable

Co-Authored-By: Terry Jan Reedy <tjreedy@udel.edu>

* Apply suggestion: Dealloccte -> Deallocate

Co-Authored-By: Terry Jan Reedy <tjreedy@udel.edu>

* Update posixmodule checksum.

* Reverse idlelib changes.
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index a04d496..a99b8ec 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -288,7 +288,7 @@
         finally:
             threading._start_new_thread = _start_new_thread
 
-    def test_finalize_runnning_thread(self):
+    def test_finalize_running_thread(self):
         # Issue 1402: the PyGILState_Ensure / _Release functions may be called
         # very late on python exit: on deallocation of a running thread for
         # example.