Text fixes (part 2)

Text fixes, second part (see #803)....

- Add 2 example files for text()
- Add Special handling for Windows Symbol fonts that do not have a Unicode charmap (e.g. Webdings)
- Add test cases for composition bug and symbol fonts (could not find a distributable font like Webdings yet, so it can only test part of the feature)

Note: The text examples have test-case images without the text as those are running without experimental features enabled. We will need to regenerate them when text() is not experimental anymore.