Squashed 'wicker/' changes from e6dc8bc..7fe0b72

7fe0b72 markov chain tweak
4805bcb some extensions to functional/predicates

git-subtree-dir: wicker
git-subtree-split: 7fe0b729ba412e29b063e9491c048c8335328b56
(wicker) markov chain tweak
skyfly spawn/despawn vs static; general optimisations