UI: planet list missing scrollbar

```
Game version: 0.95.178
Operating System: win7 x64
Java runtime version: 1.7.0_60
Installed using the Launcher? yes
Game language (en, hu, de): hu

Would be nice to have a scrollbar next to the planet list if there are more
planets than it can display in one window. Now you can only scroll by mouse
scrolling or by up/down buttons. The PgUp and PgDown buttons act weird.

Also, if you move with cursor buttons, the focus should follow the selection (I
mean, if you go up or down beyond the window, the list should scroll up or down
to follow the selection)
```

Original issue reported on code.google.com by `smfinc....@gmail.com` on 24 Jul 2014 at 12:22