Add Location

I noticed several previous attempts to create the Location file.  Each had a few things missing or off-target compared with the MC and typical plugin needs. This is my attempt to fix those short-comings and provide a coherent, simple, serializable Location class.  The minimum features selected here can be extended by future classes and should hook neatly into the MC and SpongeAPI supers.

Chunks have their own set of [x,z] coordinates and each chunks has (currently) 16 sections numbered 0 to 15.  Locations must identify these attributes in their parent chunk for ease of cross-referencing.

Location attributes include a World, [x,y,z] coordinates, and (optionally) a direction [yaw,pitch] that the location faces.

The distance and distance-squared functions are ubiquitous: universally used, well-defined, and fit neatly into the features of this class.