[feat req] Separate sums for incoming and outgoing traffic

[anatol-grabowski]

Two separate numbers would be much more informative.
E.g. with two numbers at a glance you can see if your machine is uploading something big when it's not supposed to.

[anatol-grabowski]

I've tried to (successfully) implement it a while ago, the difficulty was that there is just one variable for the total amount in the code, so my implementation was quite dirty. Unfortunately can't find my code now.