Let me choose between displays

Hello!

I finally found a working netspeed indicator for Ubuntu 14.04, but I now realize it only shows the aggregate of both incoming and outcoming traffic which is not completely useful for control freaks like myself.

Here's an idea:
-Have a menu to change the display of the speeds with two options (at least):
--Display both incoming and outcoming traffic
--Display a sum of both traffic speeds

Thank you for taking the time to read this!
(:

Start by reading the repository's C sources and locating the indicator's existing display and menu entry points. Implement the two requested display modes—separate incoming and outgoing speeds, or their sum—and verify that the menu switches between them.

Written by the indexing model from the issue text.