Allow better specifications of entities in AI goals

The AI goals only allows for entity types to be specified. For example "gather entities of type lumber".
This is too broad, as you often want to be more specific about what kind of entities you want acted on. For example "gather entities of type lumber that's at least 3 meters long".

To achieve this we need to create a simple entity matching rule system.
Like "entity.type == 'lumber' && entity.bbox.height => 3"