Using °C and °F

Hi @deanishe, perhaps I'm doing something wrong, but looking at Pint's units I should be able to use °C and °F to reference `degree_Celsius` and `degree_Fahrenheit`:

https://github.com/hgrecco/pint/blob/master/pint/default_en.txt#L198

alfred-convert is however telling me they are unknown units? Perhaps I'm misunderstanding how the units and aliases work? An option to be able to ignore case would also be nice (degC or degc). Thanks for a great workflow!!!!!