Twist and shear shader

Allows to lean the vertical features of a heightfield or procedural terrain into any direction desired. This is very useful for creating overhangs. "Twist and Shear" is good for creating large scale displacements across the entire terrain.

Settings:

      * Lean Factor: If a terrain feature was 100% upright, a lean factor of 1 would result in the terrain now leaning at 45 degrees.

      * Lean Direction [x,y,z]: The three entry fields stand for the x, y and z direction, in this order. A positive value in the x-field, for example, denotes that the lean direction is along the positive x-axis. A negative value would lean the terrain features along the negative x-axis.

      * Base Altitude: The base altitude specifies the height upward from which the Twist and Shear displacement becomes effective.