About section

[serrq]

I would like having an "about" section with some useful data within, like app version, build, app source (play store, fdroid, etc), donation button, etc.

[Sikeen]

and a link to report bugs!

[Sikeen]

or similar

[davidtakac]

App version and build can be seen in system settings. App source is not relevant because the GitHub and F-Droid builds are the exact same. Donation button is related to #8, I'll see about adding it if/when I start accepting donations.

A button that links to the source code on GitHub would be a nice addition, though. I could also point people to report bugs in GitHub issues this way. Thanks!