Add a generic Texture.GetPixels<T>() (#1117) * Added Texture.GetPixels<T>(srcRect, slice, mip, dstData, dstFormat, dstStride) * Fix reading non-zero slice from 3D texture (#1118) * CopyToStagingResource: only use 1 mip level / array slice in staging texture * CopyToStagingResource: fix copy destination offset * GetPixels: add dstSize parameter instead of dstStride * Add Texture.GetPixels3D<T>() * Texture.GetPixels( int mip ) now gets everything for array / volume textures * Added Texture.GetPixel3D() to complement Texture.GetPixel() * GetPixels: fix nativeDstRect size * GetPixels: stride fixes * GetPixels: reading from non-zero mip level fixes