[Feature] Display number of lines added & removed

[BernatBC]

First of all I'd like to express my gratitude on the awesome work you've done so far in this project. After researching for a while for a good open source graphical git client, I found sourcegit, and it's awesome. Something I miss from sourcegit is the display of the number of lines removed and added in each commit, and in each file.

It would be something like this: