Add tags yaml.list, server.max_players

Just two quick useful tags
Add tag element.format,allow newline in tags,meta

- element.format, a quick useful tag for format scripts -- also update
the format script meta
- more tag group meta, yay!
- tags can now have newlines in them - that's useful for some obscure
side cases
Fix YAML bug, entity meta

- yaml[x].list_keys would bug
- dEntity tag group meta!
Correct script.cooldown[player], fixes #705

Don't know how this backwards math managed to survive early testing.
Allow non-standard potion items

Plugin-made sorta supported and weird things like charming potions will
all work fine now, by backing up to a datavalue if the standard Bukkit
functions fail.
Merge pull request #704 from mcmonkey4eva/master

Pull request for useful little things