Fix appleseed error when appleseed version > 2.0 #116

[Rainy-fall-end]

update ArtTileCallback class according to Appleseed 1.7+

[Rainy-fall-end]

In appleseed master branch,it declares that:

class APPLESEED_DLLSYMBOL ITileCallback
  : public foundation::IUnknown
{
virtual void on_tile_begin(
        const Frame*            frame,
        const size_t            tile_x,
        const size_t            tile_y,
        const size_t            thread_index,
        const size_t            thread_count) = 0;
virtual void on_progressive_frame_update(
        const Frame&            frame,
        const double            time,
        const std::uint64_t     samples,
        const double            samples_per_pixel,
        const std::uint64_t     samples_per_second) = 0;
};
}

In appleseed 2.0+(2.0.5 beta and 2.1.0 beta)：

class APPLESEED_DLLSYMBOL ITileCallback
  : public foundation::IUnknown
{
virtual void on_tile_begin(
        const Frame*    frame,
        const size_t    tile_x,
        const size_t    tile_y) = 0;
virtual void on_progressive_frame_update(const Frame* frame) = 0;
}

[Rainy-fall-end]

I I simply updated the methods from 1.0+ to 2.0+, I'm not sure if this is still appropriate or if it's necessary to support all appleseed versions.

[drossberg]

Just some formal remarks:

• Do not comment out old code, just change what need to be changed. The version control system (i.e. git) does the bookkeeping, as you can see the the "Files changed" tab.
• You should remove the clutter from your PR ;)

[Rainy-fall-end]

Just some formal remarks:

• Do not comment out old code, just change what need to be changed. The version control system (i.e. git) does the bookkeeping, as you can see the the "Files changed" tab.
• You should remove the clutter from your PR ;)

Thanks for your comments. I have deleted it all.