Monospace code views in source and machine code views

The proportional fonts used by default can throw a lot of people off since many are used to reading code in a monospaced editor. Make it consistent by using the default system font (the fd.o name, and QFont hinting otherwise). Tested on Windows and Linux.

My concern is that this could be in the settings since fonts are pretty subjective (might not like monospace, might want a specific font) and systems often don't expose a setting for what monospace font to use (i.e on Windows it's seemingly Courier New by default, and I wouldn't know how to change it).

Looks like this: