IDLE: define word/id chars in one place.

GitHub fields:

assignee = 'https://github.com/terryjreedy'
closed_at = None
created_at = <Date 2021-11-02.16:45:21.519>
labels = ['expert-IDLE', 'type-feature', '3.11']
title = 'IDLE: define word/id chars in one place.'
updated_at = <Date 2021-11-03.11:41:19.491>
user = 'https://github.com/terryjreedy'

bugs.python.org fields:

activity = <Date 2021-11-03.11:41:19.491>
actor = 'AlexWaygood'
assignee = 'terry.reedy'
closed = False
closed_date = None
closer = None
components = ['IDLE']
creation = <Date 2021-11-02.16:45:21.519>
creator = 'terry.reedy'
dependencies = []
files = []
hgrepos = []
issue_num = 45692
keywords = ['patch']
message_count = 12.0
messages = ['405516', '405519', '405522', '405526', '405532', '405536', '405538', '405541', '405543', '405546', '405548', '405608']
nosy_count = 3.0
nosy_names = ['terry.reedy', 'serhiy.storchaka', 'AlexWaygood']
pr_nums = ['29381']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45692'
versions = ['Python 3.11']