Merge lp://staging/~hjd/widelands/osx-update into lp://staging/widelands

Continuous integration builds have changed state:

Travis build 2855. State: failed. Details: https://travis-ci.org/widelands/widelands/builds/307530399.
Appveyor build 2665. State: success. Details: https://ci.appveyor.com/project/widelands-dev/widelands/build/_hjd_widelands_osx_update-2665.

>+sudo pip install sphinx
>sudo: pip: command not found

(https://travis-ci.org/widelands/widelands/jobs/307530402=

From what I could understand, `pip` should be installed as part of python. So I added it to the `brew install` list, but that only printed that python is already installed.

Any macos users or experts who know how we might install pip (preferably through brew)?

When I run `pip install python` on my system, it prints out this caveat:

---
This formula installs a python2 executable to /usr/local/bin.
If you wish to have this formula's python executable in your PATH then add
the following to ~/.zshrc:
  export PATH="/usr/local/opt/python/libexec/bin:$PATH"

Pip and setuptools have been installed. To update them
  pip2 install --upgrade pip setuptools

You can install Python packages with
  pip2 install <package>

They will install into the site-package directory
  /usr/local/lib/python2.7/site-packages

See: https://docs.brew.sh/Homebrew-and-Python.html
---

So it might not be in your PATH and it might be called pip2.

Continuous integration builds have changed state:

Travis build 2871. State: passed. Details: https://travis-ci.org/widelands/widelands/builds/308088600.
Appveyor build 2680. State: success. Details: https://ci.appveyor.com/project/widelands-dev/widelands/build/_hjd_widelands_osx_update-2680.

That worked, thanks :)

The xcode8.3 is supposed to become the default image shortly. Since additional changes were needed here, trunk will probably run into the same problem once default suddenly changes. Can someone take a look at whether this is good to go now? I'll make another branch in a few days to remove the manuel "osx_image" option which at that point manually sets the default value...

Lgtm.

@bunnybot merge

> Am 28.11.2017 um 18:29 schrieb Hans Joachim Desserud <email address hidden>:
>
> That worked, thanks :)
>
> The xcode8.3 is supposed to become the default image shortly. Since additional changes were needed here, trunk will probably run into the same problem once default suddenly changes. Can someone take a look at whether this is good to go now? I'll make another branch in a few days to remove the manuel "osx_image" option which at that point manually sets the default value...
> --
> https://code.launchpad.net/~hjd/widelands/osx-update/+merge/334281
> You are subscribed to branch lp:widelands.