It should be possible to add more units

[MatthewStanciu]

This is going to be very not trivial to implement, but I think there should be a way to add more units. Right now the library only goes down to charges, which means that you can't build https://lightning-time.vercel.app, which goes down one unit further, using this library. It should be possible to use this library to go down as many units as you want.

Maybe instead of hardcoding this:

const millisPerCharge = 1318.359375 // 86400000 / 16^4

it would instead be millisPerSmallestUnit and then you could do like addUnit('unitName') and

ugh idk how to do this rn, but should figure it out