I know I'm late for the party, but drafted a proposal related to "Improving Behavior Trees". The idea is to allow collective behaviors for actors. Glad to receive any feedback/update the proposal accordingly - here's the link.
Did an initial review and while it is thin (no surprise with this little time) considering the circumstances it seems pretty spot on. Scope has a good feel to it, although of course it would be nice to have some more integration points with existing code, and related examples that exist at present or will exist at the conclusion of such a project
GSOC Project: Collective Behavior
Summary: Improving AI mechanisms for NPC creatures in Terasology
The main objective of this project is to develop a collective behavior mechanism for NPCs. This includes: (i) creating a collective mind mechanism for NPCs, so they can behave as a group; (ii) improving the behavior tree mechanism to allow further behavior expansion; and (iii) creating a module as a showcase/tutorial.