0024622: Add method to AIS_TexturedShape class to assign texture data directly from...

0024622: Add method to AIS_TexturedShape class to assign texture data directly from byte stream

Added methods to specify Image_PixMap as texture source to AIS_TexturedShape and Graphic3d_TextureRoot.
Modified internal class MeshVS_ImageTexture2D, originally used for the purpose of sourcing texture as Image_PixMap.

AIS_TexturedShape class:
- Get rid from cdl declaration.
- Remove unused and uninitialized field myDeflection / method Deflection().
- Improve class documentation.
- Use Graphic3d_NOT_2D_UNKNOWN instead of -1.
- Use myIsCustomOrigin and myToScale flags to use/ignore custom values.