Merge pull request #549 from blankiito/master

fix for ParticleEffect
Merge pull request #550 from blankiito/master

Add tag <player.target>
Merge pull request #551 from blankiito/master

Add sub parameter for tag <p@player.target.within[#]>
Add <in@inventory.title> tag
Allow <l@location.find.entities[creeper|zombie|player].within[x]>
Document ValueOf requirement
Merge pull request #552 from Morphan1/master

Create/Edit some tags, documentation.
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
Add filter on tag player.target

Now we can specify a npc/<entity>/<entity.type> as target.
few examples
<p@player.target[npc] will target only npc
<p@player.target[player] will target only npc
<p@player.target[e@123|e@321|zombie] will target only entity 123 or 321
or zombie