Okay, added a few more features and I'm really liking the results. I added the `-` operator for `dice_groups` which was a bit more tricky than I thought it'd be. I also added the ability to roll a dice group multiple times via a `x`|`*` operator. I removed the requirement that a dice group has to have a damage type associated with it since the only way you can roll something like `1d4-1` is in a dice group since there is a minimum value of 1 associated with it.
The code lives here: https://codeberg.org/JamesTheBard/dice-roller


