Rewrote the plugin from the ground up. More efficient in code and hopefully lighter weight on the server. Also updated the plugin to 1.13.1 for your latest update needs!
A lot of small updates including the ability to lock specific limbs in place (eg. if you find you have posed the right arm correctly and no not want to accidentally change it's position. You can lock it in place and for this session it'll stay in that position).
There may be some small bugs I haven't fully worked out, but this plugin should be able to be used in place of the 1.12.2 version in 1.13 servers. Will not work on 1.12.2!