os.system doesn't report if any of the commands fail. This means that if
something goes wrong it happily reports success making it hard to debug
issues.
LiteUSB was not up to date was not a real USB PHY but was just providing USB FIFO PHYs.
New true USB cores are now available: Daisho, ValentyUSB, so it's better using
then for true USB support. We only keep the FT245 FIFO PHY in LiteX that can be
useful to interface with USB2/USB3 USB FIFOs.
When in development mode install the packages in the user directory using the
--user flag from pip. This allows to install and run without the need for root
access.
