Baking: Cage option and skew compensation

[franMarz]

Include in the baking panel the Cage option from Bake -> Seleted to Active, in case no cage object is included in the set. Make it appears as something like "Conform to mesh normals". By now, make it on by default but warns in the tooltip about possible glitches on edges.

Additionally, study the possibility of adding a mask button to the panel for adding a texture to control skew compensation, and a reversible function to arrange the Shading Nodes accordingly.

Ideas taken from the Format64 post on BlenderArtists