Add IPDBG JtagHost functionality to OpenOCD

Add IPDBG JtagHost functionality to OpenOCD

IPDBG are utilities to debug IP-cores. It uses JTAG for
transport to/from the FPGA. The different UIs use TCP/IP
as transport. The JtagHost makes the bridge between these
two.

Comparable to the bridge between GDB and the in-circuit-
debugging-unit of a micro controller.

Change-Id: Ib1bc10dcbd4ea426e492bb7b2d85c1ed1b7a8d5a
Signed-off-by: Daniel Anselmi <danselmi@gmx.ch>
Reviewed-on: http://openocd.zylin.com/5938
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>