The plain text renderer would normally render as text anything that's not binary.
The plain text renderer would normally render as text anything that's not binary.

However, there are a few formats (mainly PDF, RTF, etc.) that are not
detected as binary, but not human readable either...

For the time being, we maintain a list of this kind of format 
which should be treated as binary.

Fixes #1920.


pkdevbox/trac,pkdevbox/trac,pkdevbox/trac,pkdevbox/trac