CLI is awkward to use

[svenstaro]

Describe the bug I think the CLI is a bit awkward to use and overuses subcommands in favor of flags.

To Reproduce For instance, menyoki record --root --size $(slop) apng save /tmp/hello.apng. This is somewhat awkward.

Expected behavior How about menyoki record --size-select --format apng --output /tmp/hello.apng. I think this makes a lot more sense. We could also have a shortform -f apng -o /tmp/hello.apng.

[AlexDaniel]

Related: https://github.com/orhun/menyoki/issues/43