Add handle on environment texture in OpenGl_Workspace.
Add a new parameter UseEnvironmentTexture to the Graphic3d_ZLayerSettings.
OSD layers don't use environment texture by default.
zbuffertrihedron doesn't use environment texture.
vzlayer can enable/disable environment texture mappping.
Delete unnecessary files Graphic3d_TypeOfSurfaceDetail.hxx and V3d_TypeOfSurface.hxx.
Delete functions SurfaceDetailType and SetSurfaceDetailType functions from Graphic3d_CView.
Delete functions SurfaceDetailState and UpdateSurfaceDetailStateTo from OpenGl_ShaderManager.
Delete class OpenGl_SurfaceDetailState.
Delete functions SurfaceDetailType and SetSurfaceDetailType from OpenGl_View.
Delete functions SetSurfaceDetail and SurfaceDetail() from V3d_View.
Delete functions SetDefaultSurfaceDetail and DefaultSurfaceDetail from V3d_Viewer.
Delete draw command VSetTextureMode.
Add description in dox.
