Gameplay update

Update gives greater player agency and direction.

Buildings now stack on top of others of the same type, so as a player you want to merge the same animals in the same areas to conserve island space. 

Movement is also slightly more predictable (only move when new animal spawns, usually to find a mate or get away from the spawned animal) and can be better affected by the player (push animals away by spawning on them or spawn elsewhere to trigger their movement towards a nearby mate).

...the drab building colours will be replaced soon enough...