Stephan told about the intended use case for --invisible, and it does sound
like a plausible use case, so let's revert this.

   "ah, now that I see 4fe56f3b: one use case
    for invisible + !headless might be in workflows where external code keeps
    a LO instance running and lets it pop up document windows, but you don't
    want the initial start center thing

    I think that's historically where the --invisible thing is coming from, now
    that I vaguely remember again"

This reverts commit 4fe56f3b.

Change-Id: I17f535adee7e533abbee150b0ce5156ecf78c781