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/Objects/exceptions.c b/Objects/exceptions.c
index 568d495..ef9dd51 100644
--- a/Objects/exceptions.c
+++ b/Objects/exceptions.c
@@ -405,7 +405,7 @@
     BaseException_new,          /* tp_new */
 };
 /* the CPython API expects exceptions to be (PyObject *) - both a hold-over
-from the previous implmentation and also allowing Python objects to be used
+from the previous implementation and also allowing Python objects to be used
 in the API */
 PyObject *PyExc_BaseException = (PyObject *)&_PyExc_BaseException;