Remove unnecessary columns, switch to .xls (it's what the assembly houses seem to want) and make the references consistent.

- Smaller apertures overall
- Larger apertures for LED
- Totally redo the LQFP apertures for U1

Changed the shape of pads for U1 and U3, trying to avoid having too much solder paste.

Missed a commit, oops.

If we issue a short write, libwebsocket handles it kinda ungracefully and we have no idea when to close the socket. Instead of letting libwebsocket copy our content into a temporary buffer, we can just give it smaller pieces.