Allow to rename a node

[pleonex]

Rename nodes

Issues:

• We cannot rename a node, we need to create a new one, dispose old, change node
• It could affect paths but that's expected, we shouldn't store them.
• Problem is when the new name conflicts with another node in the parent

Proposal:

• Implement setter
  • Check if it's invalid
  • Check if another child in the parent has the same name