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_compileall.py b/Lib/test/test_compileall.py
index 04f6e1e..99d8437 100644
--- a/Lib/test/test_compileall.py
+++ b/Lib/test/test_compileall.py
@@ -578,14 +578,14 @@
             self.assertEqual(compile_dir.call_args[-1]['workers'], 0)
 
 
-class CommmandLineTestsWithSourceEpoch(CommandLineTestsBase,
+class CommandLineTestsWithSourceEpoch(CommandLineTestsBase,
                                        unittest.TestCase,
                                        metaclass=SourceDateEpochTestMeta,
                                        source_date_epoch=True):
     pass
 
 
-class CommmandLineTestsNoSourceEpoch(CommandLineTestsBase,
+class CommandLineTestsNoSourceEpoch(CommandLineTestsBase,
                                      unittest.TestCase,
                                      metaclass=SourceDateEpochTestMeta,
                                      source_date_epoch=False):