This patch enables to specify extra non alphabetic characters that go into identifiers, and to disallow optionally underscores and accented characters. Except for the latter, one can differentiate between starting and non starting characters - some languages disallow say _ as the first character.
This applies to identifiers, and not to keywords.
Requires: patch #3089258 UDL handling enhancements and corrections
UI impact: A new tab called Characters is created on the UDL panel. It may feature other config enhancements in the future.