v1.3

Added compiled binary for the STM32F401 microcontroller. This microcontroller is significantly faster than the Atmega328p and supports DMA (direct memory access) so we can achieve more efficient ADC sampling.
The symbol rate of the STM32F401 is 200kHz with an ADC sampling rate of 40kHz. There is also significant remaining headroom for even faster sampling speeds if it is desired.

NOTE: The effect of multipath fading results in a less stable PLL and TED lock as the symbol frequency increases.