Support more types of OLED displays

Updated for SysTick IRQ example for latest changes in ch32v003fun library.

Fix spacing to clarify behavior, and, also, improve algebra for microseconds. If a delay is much too long it at least has a shot at having a compiler warning.

Redo reverted patches for MacOS 

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