Symbian socket engine: WINSCW emulator + wintap

The R&D environment (and defunct symbian PDK) use the real symbian TCP/IP stack with the wintap driver to exchange raw packets with the ethernet interface of the host machine. This is similar to how virtual machines work (although WINSCW is just a single native process running a modified symbian kernel in user mode).

We should test this works, but I had some trouble to set it up on my PC due to broken configuration files in the symbian PDK.