* Add: Cmake otion to hide line numbers in doxygen warnings.
* Add: Cmake options to specify output file for doxygen warnings.
Adds 3 options each one for each docs target, because doxygen deletes
content of the specified file before it begins to write into it.
This means we have RTL support again with ICU 58+. It makes use of:
- ICU for bidi-itemization
- ICU for script-itemization
- OpenTTD for style-itemization
- harfbuzz for shaping