Amazing jumping nodes

Nodes don't stay where I put them.

```
library(RNetica)
sess <- NeticaSession()
startSession(sess)
anet <- CreateNetwork("anet",sess)
anode <- NewDiscreteNode(anet,"anode")
NodeVisPos(anode) <- c(2,2)
NodeVisPos(anode)
```

Expected:
```
 x  y 
2 2 
```

Actual:
```
 x  y 
69 27 
```

This appears to work correctly if I change 2,2 to 100, 100.
