[Feature Request] Min/max GOP length info column

[zhguyu]

It would be excellent if we can know the min and max GOP length of the video file in the info column, and probably the size of the specific GOP the mouse is hovering over in the GOP-based chart.
The motivation is that sometimes when I transcode video with x264/x265 I would set --keyint and --min-keyint to balance between seek time and bitrate, but I'd like to know what will be the outcome and if it's actually worth it.