Issue #27626: Spelling fixes in docs, comments and internal names

Based on patch by Ville Skyttä.
diff --git a/Lib/idlelib/ParenMatch.py b/Lib/idlelib/ParenMatch.py
index 19bad8c..47e10f3 100644
--- a/Lib/idlelib/ParenMatch.py
+++ b/Lib/idlelib/ParenMatch.py
@@ -9,7 +9,7 @@
 from idlelib.configHandler import idleConf
 
 _openers = {')':'(',']':'[','}':'{'}
-CHECK_DELAY = 100 # miliseconds
+CHECK_DELAY = 100 # milliseconds
 
 class ParenMatch:
     """Highlight matching parentheses