Add Bot window

[nikkorn]

Add a bot window where bots can be added (maybe dragged into position).

The editor will behave normally UNLESS there is at least a single bot on the bot window, in this case there will be a bot selector field for our definition and board (which will take a 'bot' and 'world' object that will have all the cool methods on) and the run button will execute for ALL bot behaviour tree instances.

Maybe we just have two editors? One standard one with definition and board like normal and one where the bot window is showing and we always have a default bot but others can be added.

We also might want a pre-simulation script that takes a 'world' argument and sets everything up before starting.