Support for disabling nodes

[Flynsarmy]

Problem statement

While making a behaviour tree, it's common to not know exactly what you're doing and during the debug process want to keep a branch in the tree but have it not execute. Deleting and remaking entire branches can be tiresome and time consuming.

Proposed solution

Add a 'enabled' checkbox on all nodes, checked by default. Alternatively add a 'disabled' checkbox, unchecked by default. Any node not enabled will not execute, including any of its children.

Alternatives

It can be worked around by deleting and re-adding the node. But doing that loses all configuration which has to be redone after adding back.