fine tune fragment/playlist loading retry mechanism

   404 on playlists
        On initial load (.m3u8 never previously loaded), a single 404 error triggers no retries. an error is triggered
        After initial load, a 404 error will trigger retries every 1s,2s,4s,8s (exponential). the max nb of retry should be customizable with specific handling for these 2 values :
            0, means no retry, error message will be triggered automatically
            -1 means infinite retry

    404 on segments
        a 404 error will trigger retries every 1s,2s,4s,8s (exponential). the max nb of retry should be customizable with specific handling for these 2 values :
            0, means no retry, error message will be triggered automatically
            -1 means infinite retry

related to https://github.com/mangui/HLSprovider/issues/160