Add additional time to start and end of run

[megmacattack]

I always wind up slightly altering the start and end times of my vods to include a bit of lead up and post-end (partly because my cap card has some delay). It'd be nice to be able to control this in the autohighlighter UI instead of having to go back a step on the twitch vod editor page and manually do it.

Basically just a couple of text fields for how many seconds to add at start and end of vod.

[Dalet]

For now you can edit the buffer time in the settings, it affects both the start and end though.
Ideally you would have separate settings for each game.