Simpler controls, NPC AI in progress

This update modifies/simplifies the controls a little bit. From now on, you don't have to keep holding the button to pick stuff up, just tap it once and wait for it to beam up. Movement speed is severely reduced while a block is being picked up, but only until it reaches the "cargo altitude": you can move around full speed once the block turns red. You can also cancel pickups by tapping the button or moving away from the block.

Worker NPCs will now look for nearby rocks/trees (and at the moment they "destroy" them immediately as a PoC). They also express their intention (waiting around / going for resources) with icons.

We've also replaced the default Construct 3 sprite font with one that is in the asset packs of the jam.