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_collections.py b/Lib/test/test_collections.py
index e532be6..0119c77 100644
--- a/Lib/test/test_collections.py
+++ b/Lib/test/test_collections.py
@@ -424,8 +424,8 @@
 
         self.assertIsInstance(p, tuple)
         self.assertEqual(p, (11, 22))                                       # matches a real tuple
-        self.assertEqual(tuple(p), (11, 22))                                # coercable to a real tuple
-        self.assertEqual(list(p), [11, 22])                                 # coercable to a list
+        self.assertEqual(tuple(p), (11, 22))                                # coercible to a real tuple
+        self.assertEqual(list(p), [11, 22])                                 # coercible to a list
         self.assertEqual(max(p), 22)                                        # iterable
         self.assertEqual(max(*p), 22)                                       # star-able
         x, y = p