Fix references

[Gigahawk]

This pull request fixes all of the broken references in the main schematic. I couldn't find where the symbol for the USB connector comes from, so I rewired it to the equivalent symbol in the standard library.

There was also a broken reference in the PCB to the main crystal Y1, this has been fixed as well.

I'm not entirely sure why all of the footprints reference cftkb.pretty, but that appears to be intentional so I've left it unchanged. In my opinion it would make more sense for all of the footprints to use the ones from the standard library and only use cftkb.pretty for footprints specific to this project like the Discipline symbol.