Remove .h files, pull code into top, clean up GPIO setup.

 * In unbrick mode, revert previous change that left the processor hanging.

Make minichlink able to be usd as a library + let it read/write debug registers on the device directly from command-line.

add support NHC-Link042 to minichlink

 * Allow for older __riscv__ predefine'd checks.

Add support for macOS

Add ADC/DMA/Op-amp example

added font scaling to the i2c_oled example

GPIO example expanded by ADC functions, additional ADC example

added systick_irq_millis example

I2C example readme pins were swapped

cnlohr's separate putchar() for UART and Debug for speed.