Add two autotests

Add two autotests

- The first test makes sure that the width of the places panel
    doesn't change no matter what other panels are shown or hidden.
    There used to be bugs about this.
- The second test is kind of an integration test. It makes sure
    that the go actions work correctly. On two occasions we had
    the regression here that after going "Up" in the file system
    hierarchy the folder one emerged from didn't have keyboard
    focus which makes peeking into multiple folders tiresome.
    The test also makes sure that going back and forward works
    as expected and there are some sanity checks about which
    go actions are enabled, which items are selected and that
    using tabs doesn't interfere with any of that.