Fix the tree file version constant.
Fix the tree file version constant.

This was what was causing #137.
Didn't notice until I realized that it was keeping the old 1.6 file around instead of autoupdating it.

PrinceOfAmber/inventory-tweaks,TGNThump/inventory-tweaks,mrammy/inventory-tweaks,asiekierka/inventory-tweaks,mrammy/inventory-tweaks,GuntherDW/inventory-tweaks-liteloader,TerraGamingNetwork/inventory-tweaks,asiekierka/inventory-tweaks,PrinceOfAmber/inventory-tweaks,Kobata/inventory-tweaks,TerraGamingNetwork/inventory-tweaks,TGNThump/inventory-tweaks,GuntherDW/inventory-tweaks-liteloader