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/Misc/HISTORY b/Misc/HISTORY
index f4b756c..f49960c 100644
--- a/Misc/HISTORY
+++ b/Misc/HISTORY
@@ -2113,7 +2113,7 @@
 - Issue #21285: Refactor and fix curses configure check to always search
   in a ncursesw directory.
 
-- Issue #15234: For BerkelyDB and Sqlite, only add the found library and
+- Issue #15234: For BerkeleyDB and Sqlite, only add the found library and
   include directories if they aren't already being searched. This avoids
   an explicit runtime library dependency.