Implemented the skeleton code for the beacon.
There is no handling for the GUI. It can now check how big the pyramid is under the beacon.
Simplefied GetPyramidLevel
Removed debug message.
Some tweaks
GetPyramidLevel returns 0 when no layers were found, 1 for one layer etc.
Auto adjust the minY and/or maxY to 0 if the beacon is low.
Fixed #904
Fixed #906
Merge branch 'master' of https://github.com/mc-server/MCServer
Compilation fix
Merge remote-tracking branch 'origin/Beacons'
Fixed formatting, made function static.
APIDump: Added a ChunkStay article.

Fixes #772.