 sfifo53 - s(imple) driver for 16650 based rs232 interface
 sswiftlink - s(imple) driver for swiftlink cardridge
 srs232_std - s(imple) driver for standard userport rs232 interface (incomplete)

 swiftlink - driver for swiftlink cardridge

The simple drivers have a different API (including getc and putc functions)
easier to handle, but quite limited (busy-wait-getc/putc) and not suited
well for TCP/IP stuff.
Microterm and getty rely on this simple API.

i moved tcpip, slip, ppp and loop into the apps directory because they are
not dependent on the machine at all. Machine independent stuff should go
into the application directory.
