Added new features for the decal shooter tool

[klaussilveira]

Added some new features to the Decal Shooter. Thanks to Anton for the ideas.

• Autogroup: when checked, all decals are automatically added to the same selection group
• Flip: when checked, the decal is flipped to acomodate decals facing the opposite direction
• Layer: when a layer is selected, all decals are automatically added to that layer
• Rotation: apply this rotation to the decal before applying to the surface
• Random rotation: apply a random degree to the rotation of the decal

decalimp.mp4