Advanced Terrain Manipulation

I don't know if this should technically be separate feature requests but combined they kind of sum up the total of where I would like terrain manipulation to reach:

• Import/export of terrain heightmaps to define terrain
• Import of custom terrain textures
• Import of advanced textures beyond rgba; Think specular map, luminosity map, roughness map… basically be able to create a whole "material".
• a "stack" (imagine photoshop layers) of textural data that can be combined/mixed/masked before projection to the terrain