HTerrain plugin demo project

This is a demo of the HTerrain plugin I made for Godot Engine 3.
It exists as a separate repo in order to keep the core repository clean.

This plugin is required: https://github.com/Zylann/godot_heightmap_native_plugin
It is bundled with the demo to make it work out of the box. If any problem arises, check first if a new version is available, because I don't update the demo as frequently.