[En-Nut-Discussion] More Nut/OS enhancements

[Harald Kipp]

The USART driver seems to work now. However, I didn't
test synchronous mode, but software and hardware
handshakes work fine. I'm still unsure about 9-bit
communication and I have to look into the optimization
of NutPostAsync.

Michael Fischer contributed an IDE driver update.
It will be easier to adapt it to different hardware.
Additionally it has been implemented on a low cost
implementation, where external memory and IDE interface
share port pins, similar to Jesper Hansen's YAMPP
hardware.

Harald