Added flag for centring mouse when activating window

[Rublis]

No description provided.

[mkropat]

That's a neat idea. I see no reason not to add that functionality. Give me the rest of the day to play around with it just to double check that it works as expected. If I don't find anything I'll merge this and release jumpapp 1.0 😄

[mkropat]

I didn't get a chance to test it this weekend, since I ended up spending the whole weekend preparing a presentation I'm giving Monday.

If someone else has a chance to test this out and report back, that's good enough for me. Otherwise I'll see if I have time to test it out sometime during the next week.

[mkropat]

Thanks again for the PR.

I changed the flag letter from -m to -C (for "center"). I hope you don't mind. That way we can save -m for #11 if we ever implement that.

If anyone wants to help test the code in master, I'd appreciate it, since I made a few changes beyond just adding the new flag. I want to give it a week or two, and if no one reports problems I'll go ahead and tag it version 1.0 and push a new .deb out to the PPA.