Update version to 2.13.1-SNAPSHOT

Draft for version 2.13

Fix for #147

pre-release for 2.12

Merge pull request #126 from Mooselk/master

Fix NPCState#CROUCHED for 1.14.x -> 1.16.x

Merge pull request #121 from Mooselk/master

Look at location method + 1.16.x support

Added method NPCManager#getShownToPlayer

Removed support for 1.8 R2

Added support for 1.16

Updated version to 2.7.2-SNAPSHOT