[Feature request] plugins prefix

Hello :) I'm quite interested in this project, and one thing I think would be pretty useful in terms of usability is provide a way to allow the user to set a prefix for plugins, so it's easier to directly target some plugin without relying too much on fuzzy matching and stuff example: if I want to run a shell command from centerpiece, I could prefix it with `!` ``` !pkill something ``` or if I want to do math I use `=` ``` =150 + 50 ``` (I know my examples are not currently implemented in centerpiece, but they demonstrate my point better) I'm not sure if you're interested in adding this feature, so let me know what you think, and maybe a better way to implement something like this :)