Show node preset panel in main view

[bitbrain]

It is cumbersome to compose a beehave tree, as you always have to add the nodes by hand. Instead, we could show a side panel where when clicked nodes get automatically added to the scene tree. That side panel could contain presets such as:

• composite nodes
• decorator nodes
• blackboard helper nodes

The side view should only be visible if a node of type beehave tree or beehave node is currently selected.