Added: qdec, a header only quadrature encoder library
Added: EXTI15_10_IRQHandler to handle the encoder knob
Changed: platform_init() for the MD-UV380 now configures the EXTI15_10
interrupt.
Changed: platform_getChSelector now returns signed int8
Changed: size of settings_t.valid went from 6 to 7
Without this change, pressing the macro button crashes the radio, I
haven't investigated and I don't remember how I found that solution.
Changed: meson.build includes the qdec library