VNC support

Needs libvncclient
Useful if you want to do something else with your mouse/keyboard while sikuli is running

Use it like...

```python
vncscreenid=JScreen.connectVNC(["vncviewer","192.168.1.111"],"password")
vncscreen=Screen(vncscreenid)

# Then everything will have to be accessed via the new "vncscreen" object.

vncscreen.click(Location(1,1))
vncscreen.type("abc")
vncscreen.find("xxx.png")
```