Start previously run emulator

Hello,
First of all allow me to thank you for this nifty little library. I love it.
One feature I wanted to suggest was the ability to pass an argument such as "emus -p" to start the previously used emulator with all the arguments it was run with. I think it's worthwhile to have.

Though not having it in no way diminishes the value of your lib.
Thank you, and have a wonderful day!