new column in exif-data for exif field description

[FlorianH]

I think it would be usefull to have an extra column 'description' in the EXIF data dialog and in the external exif text files (see this topic).

It's sometimes very difficult to find a short and adequate translation for the english exif tags. So i would keep the english label (perhaps because advanced users are used to it) and give a description in native language.