Removed unused files
Added license (right click this wallpaper, click 'Open in Explorer' then open license.txt to see it.)

After this update, HTML files can be used as a background. See (Open in Explorer)\bghtml\readme.txt to learn more.

Note: attempts to implement directly importing HTML backgrounds had failed for the following reasons:
* Wallpaper Engine's user properties don't support selecting HTML files.
* WE's browser engine (CEF) does not allow accessing local files that are neither inside the wallpaper directory nor imported by the user in user properties.
* Importing with <input type="file"> + JavaScript FileReader can't load the resources required by the HTML background.
* Uploading them on a remote web server is just inappropriate for this feature. (Active Desktop allowed only local files, too.)