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/lib2to3/fixer_util.py b/Lib/lib2to3/fixer_util.py
index babe6cb..c2a3a47 100644
--- a/Lib/lib2to3/fixer_util.py
+++ b/Lib/lib2to3/fixer_util.py
@@ -412,7 +412,7 @@
     return None
 
 def _is_import_binding(node, name, package=None):
-    """ Will reuturn node if node will import name, or node
+    """ Will return node if node will import name, or node
         will import * from package.  None is returned otherwise.
         See test cases for examples. """
 
diff --git a/Lib/lib2to3/tests/test_parser.py b/Lib/lib2to3/tests/test_parser.py
index 01b2b51..f22d399 100644
--- a/Lib/lib2to3/tests/test_parser.py
+++ b/Lib/lib2to3/tests/test_parser.py
@@ -531,7 +531,7 @@
 
 # Adapted from Python 3's Lib/test/test_unicode_identifiers.py and
 # Lib/test/test_tokenize.py:TokenizeTest.test_non_ascii_identifiers
-class TestIdentfier(GrammarTest):
+class TestIdentifier(GrammarTest):
     def test_non_ascii_identifiers(self):
         self.validate("Örter = 'places'\ngrün = 'green'")
         self.validate("蟒 = a蟒 = 锦蛇 = 1")