Regex replace arguments

Here's a quick rundown of how this can be used.

Anything you want to match/replace has to be surrounded by parens.

For example, event line: The condition of your (.*) has dropped to (.*)%
$0 becomes: The condition of your stupid hat has dropped to 10%.
$1 becomes: stupid hat
$2 becomes: 10

Arguments require quotes when they have spaces (and quotes are always safe) so an argument like this:
/full "$0" /item "$1" /percent "$2"
Becomes:
/full "The condition of your stupid hat has dropped to 10%." /item "stupid hat" /percent "10"