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_trace.py b/Lib/test/test_trace.py
index 912badb..7cda546 100644
--- a/Lib/test/test_trace.py
+++ b/Lib/test/test_trace.py
@@ -180,7 +180,7 @@
         firstlineno_called = get_firstlineno(traced_doubler)
         expected = {
             (self.my_py_filename, firstlineno_calling + 1): 1,
-            # List compehentions work differently in 3.x, so the count
+            # List comprehensions work differently in 3.x, so the count
             # below changed compared to 2.x.
             (self.my_py_filename, firstlineno_calling + 2): 12,
             (self.my_py_filename, firstlineno_calling + 3): 1,