Prevent event duplication

A quick fix to trim away extra events if they somehow wind up cloned
(EG, item.identify() and material.identify() both lining up)
An existent example: on player shoots bow: fires twice without this
commit.
Clean element.is.than error handling

Two fixes:
- 'less' is now permitted in addition to 'LESS' (case-insensitive)
- a fully bad operator (EG '.is[potato]') will respond with a simple
error message rather than a full stacktrace.

Also, player.target, return Element.NULL rather than a real null
pointer.
Add element.totitlecase

Returns The Element In Title Case.
(Named as such to prevent conflicts with such tags as 'inventory.title')
Pretty straightforward tag
Add location.yaw.simple

Returns north/south/east/west
Again, straightforward tag.
Prevent ParticleEffect errors + clean meta

This will prevent the ParticleEffect from throwing errors when
accidentally sending Effect packets to NPCs.
Also cleaning up some meta and error messages for English readability.
Small meta corrections

My bad
Merge pull request #553 from mcmonkey4eva/master

Request pull