Missing a SetValue graphNode

[Boivin92]

There's a ReadValue node (the Condition GraphNode) but no method of setting anything. I'd like a graph-node similar to Condition but with a value field in addition to the Path one to easily change values.

I suggest that it calls a method rather than do a hard Set, so it's a bit more flexible on the use-cases.

I'll try and implement something in the coming days.