Introduce a Mask Building System

[arunoda]

Here using the Landscape Height & Other information, we should be able to create some masks. These are not "paint layers". But some masks.

We can create a mask using the following things:

• Height Data
• Normal Data
• Noises
• Edge Noises
• Merge with an existing mask (use operations: add, multiply or subtract)
• Merge with an existing paint layer (use operations: add, multiply or subtract)
• Painting Manually
• Paint geometry shapes
• Project a static mesh

Here are set of things that we can do with masks:

• Apply paint layers
• Use for applying landscape height (noises, etc)
• Directly send them to the material for additional work
• Access these via Blueprints (for foot sounds & other effects)
• Spawn Foliage