Option to convert fahrenheit to celsius

[tito]

My Nvidia card give me fahrenheit information which i don't understand :)

[pkkid]

Similar to bug #3, you could edit the theme file at <pkmeter>/share/themes/default/layout.html and change the references from temp_f to temp_c to get the desired output.

That said, both this and the time format seem like they may be general enough to include a setting someplace, so I'm leaving them open for now.