Fix build for !curses
Set the avalon read transfer latency to avoid sleeping when no data is returned after very short latency settings.
Merge pull request #435 from kanoi/master

FTDI Latency
Merge pull request #436 from kanoi/master

usbutils optional read buffering
Merge pull request #437 from kanoi/master

usb_ftdi_set_latency
Icarus use buffered USB reading