feat(hungerrain): add initial implementation of hunger rain

Add the initial implementation of the HungerRain plugin. This includes all basic features.
feat(debug): add  command for in game debug info
fix(isExposed): respect transparent blocks that prevent movement

World#getHighestBlockAt(location) ignores blocks which allow light to pass. Fix this with a manual iteration upwards until hitting either an occupied Block or the World#getMaxHeight(). Add a test which verifies expected Bukkit behavior.
chore: bump version to 0.1.0