Merge pull request #1124 from emanuelschuetze/translations

Final update of all languages for 1.5: CS, DE, FR, PT.
translate lanuage names in global_settings

Fixes: #1118
Merge pull request #1119 from ostcar/translate_languages

translate lanuage names in global_settings
Prepare handbook for 1.5.
Update documentation
Updated documentation for 1.5

- Updated all screenshots.
- Improved image handling with autoimage extension.
- Some minor content updates for 1.5 version.
- Fixed wrong list of speakers icon.