Dynamically configure network connections of running QEMU VMs

To use Qemu v0.11.0 following patches to Qemu are needed:
https://github.com/shmygov/qemu-0.11.0-patches-for-gns3

To use Qemu v0.14.1 following patches to Qemu are needed:
https://github.com/shmygov/qemu-0.14.1-patches-for-gns3

These include new patches not contained in http://www.gns3.net/qemu/:

0003-qemu-0.11.0-monitor-udp.patch
0003-qemu-0.14.1-monitor-udp.patch

More testing needed with new Qemu versions.