Converts colored images to 8-, 12-, and 16-Bit gray scale image.

Change colored image into gray scale to add an artistic range of gray shades and create a smaller file size.
| Framework | Member |
|---|---|
| .NET | GrayscaleCommand |
| .NET 6+ | GrayscaleCommand |
| iOS / OS X | LTGrayscaleCommand |
| Java | GrayscaleCommand |
| C DLL | L_GrayScaleBitmap |
| C++ Class Library | LBitmapBase::GrayScale |