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/asyncio/streams.py b/Lib/asyncio/streams.py
index 204eaf7..e56e2ef 100644
--- a/Lib/asyncio/streams.py
+++ b/Lib/asyncio/streams.py
@@ -556,7 +556,7 @@
             # Avoid inheritance from FlowControlMixin
             # Copy-paste the code to your project
             # if you need flow control helpers
-            warnings.warn(f"{self.__class__} should be instaniated "
+            warnings.warn(f"{self.__class__} should be instantiated "
                           "by asyncio internals only, "
                           "please avoid its creation from user code",
                           DeprecationWarning)
diff --git a/Lib/asyncio/subprocess.py b/Lib/asyncio/subprocess.py
index e6bec71..2a68c9e 100644
--- a/Lib/asyncio/subprocess.py
+++ b/Lib/asyncio/subprocess.py
@@ -130,7 +130,7 @@
 class Process:
     def __init__(self, transport, protocol, loop, *, _asyncio_internal=False):
         if not _asyncio_internal:
-            warnings.warn(f"{self.__class__} should be instaniated "
+            warnings.warn(f"{self.__class__} should be instantiated "
                           "by asyncio internals only, "
                           "please avoid its creation from user code",
                           DeprecationWarning)