Redo of #2939 rebased against RCBugFix

Apply `ENABLED` / `DISABLED` macros to language-related files.

Cleaned typo in language_test.h Cyrillic part.

Automatic selection was to unflexible.

Updated documentation

Updated language files to new logic and documentation.

Updated bdf2u8g.exe

Improve description in Configuration.h

Will show the compleet utf8 or ASCII charset
To se the second half of ASCII click on "01234..."