writing settings can cause usb devices to malfunction

[delan]

• affects pcb rev A3 and firmware 1.5
• affects Microsoft Wheel Mouse Optical 1.1A (045E:0040)
  • writing settings has a >20% chance of causing malfunction
  • red led goes dim, mouse spews reports until disconnected
• probably due to suspending interrupts and pausing the other core when writing to flash
  • same failure if you replace Settings::write impl with just noInterrupts() + sleep_ms(5) + interrupts()

[delan]

workaround in firmware 2.0: settings are now saved when you close the menu, and you can hold Shift to reboot the adapter after saving (Shift+Enter).