I just found that today and it looked like a good thing to share. Especially the option to compile your C++ script later on into native seems to be very sexy
The interpreter is GPL, but the library can be used under LGPL.
ARTIFEX TERRA 3D - Artist-friendly, free and easy WYSIWYG realtime outdoor scene Editor & Painter
New loader now with Ogre::Terrain support: Addons for Artifex on SourceForge
MOC - Minimal Ogre Collision & Mousepicking
Simple TerrainMaterialGenerator for the use of standard Ogre material with Ogre::Terrain
Support me on Patreon

ARTIFEX TERRA 3D - Artist-friendly, free and easy WYSIWYG realtime outdoor scene Editor & Painter
New loader now with Ogre::Terrain support: Addons for Artifex on SourceForge
MOC - Minimal Ogre Collision & Mousepicking
Simple TerrainMaterialGenerator for the use of standard Ogre material with Ogre::Terrain
Support me on Patreon