Export scene change to ``# keyframe format v1``

[moi15moi]

Problem/Use Case

Export the generated scene list to a file and import them to aegisub.

Solutions

Be able to export # keyframe format v1 file with the cli.
This is a old format that some tool, like aegisub, use to represent the scene detection.

Examples:

keyframe format v1 format is really simple.
The first 2 lines are always theses (you can technically set an fps, but it doesn't do anything. Most parser just skip the fps line):

# keyframe format v1
fps 0

After that, each line will contain the frame number where a scene change is detected.
Ex:

# keyframe format v1
fps 0
0
120
156
343