Add spread argument to the shoot command

Can now spread the entities rather than mount them
Add a config option for the ex help info

Turn off this config option if you're annoyed by the message firing
every time you use /ex
Improve shoot spread math

Several hours of work result in... deciphering basic 3D vector rotation
math!
Add EntityCritical property for arrows

You can now set arrows to 'critical' mode (fancy flying stars and extra
damage)
Also some meta interlinking.

Also, random arbitrary half-add of this to the previous commit... git is
still weird.
Improve Skull_Skin property

Now works for any skull_item rather than only head items.

Also more meta-interlinking
Add util.date.time.duration, fix potion prop

- "Regen" and "Regeneration" -> the same potion, different names,
because some genius at Bukkit had two similar but different enums.
- and util.date.time.duration to go along with player.first_played and
tags like that.
Add some math tags and some meta

- trig math functions
- group meta tag... we need that all over the place, for better
organizing!
- also, patch a warning meta
Add player.ip.address, command meta

- player.ip.address to match 'on server list ping's 'context.address'...
a standard IP address.
- group command metas, add missing authors...
Add tag player.item_in_hand.slot

A quick tag for the slot # of a player's selected item.
Add golden apple property, more meta work

- a proper for whether golden apples are enchanted
- mechanism tag for easy property meta-interlinking
Merge pull request #697 from mcmonkey4eva/master

Pull request for new features