Allow a child node to be re-linked to another parent node

[cluxter]

Current behaviour

We can't modify the link between a parent node and a child node. Thus every time we need to affect some child nodes to another parent node, we must delete them all and re-create them one by one. This makes the tool of very limited use.

Expected behaviour

The link between two nodes can be modified to be affected to some other node.

[cedoor]

Hello @cluxter,

this is an interesting mmp library feature. However, it has already been planned the possibility to copy and paste a node #2. For the moment I hope I can finish this.

In any case, I leave the issue open for future implementations, thanks!