Fix text() CSG output and cleanup test cases.

- enable text feature in import-export test cases
- drop ParaType font as Liberation is needed for the composition regression
  test, so use this for other tests too
- drop Amiri bold font, which is not adding anything to coverage
Add paste button to font list dialog.
Add filter for font table.
Enable text for most test cases and update reference images.
Read font index from fontconfig and check result from FcPatternGet().
Accept Macintosh/Roman charmap and always dump charmaps (as debug output).
Merge pull request #871 from openscad/text-fixes-3

Text fixes (part 3)