Feature Request: Show summary

[Igor Adamenko]

Usually when I use Optimizt I compress a batch of images and wanna know how much space I have saved for my users. But as a result I get this:

$ optimizt --lossless *
ℹ Lossless optimization may take a long time
✔ 1.jpg
   54.421 KB → 36.374 KB. Ratio: 33%
✔ 10.jpg
   75.561 KB → 52.14 KB. Ratio: 31%
# ...
✔ 98.jpg
   40.487 KB → 36.02 KB. Ratio: 11%
✔ 99.jpg
   47.82 KB → 42.492 KB. Ratio: 11%

✔ Optimizing completed
  Done!

It's cool, but I want to know the total stat. I would be great to add it.