Automatically handle font issues

• I have DejaVu at /usr/share/fonts/TTF/DejaVuSans.ttf which seems like a standard location, why is it not recognized?
• I don't think mtn should error-exit when it finds no font and is called without -i -t but simply spit out a warning and omit these texts automtically, this would make quick usage much easier.

Sorta follow-up to #43 (closed)