Feature request: user configurable default zoom level

[Yekutiel]

I like using Converseen instead of trying to figure out how to get Ffmpeg to do what I want from a shell.

I normally choose to shrink my images by 50% * 50% each time I compress them with Converseen. Therefore, of course, I'd like to set the default zoom level to 50% * 50%.

Thanks for creating this cool utility!