Added donors with demo in pucks.worlds.dev.world11.
Added variable world pucks.worlds.ai.world5.
Don't find neighbors of beacons.
Changed inventory implementation; added ai.world6.

Changed inventory from set to vector.
Added pucks.worlds.ai.world6, which is a variable world including vents
in boxes with gates and a nursery for key donors.
Version bump.
need upstream

acking branch 'upstream/master'

# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
#
# Lines starting with '#' will be ignored, and an empty message aborts
# the commit.