test travis on py2.6 too

travis: pip install obspy with `--no-deps` (all dependencies are
installed in "pre-install" section, avoids re-installing newer
scipy, see https://travis-ci.org/megies/obspy/jobs/13862500)

debug missing suds in travis

travis: properly install dependencies for py 2.6 test run

travis: try to fix installation of py 2.6 build dependencies of dependencies
Merge branch 'master' into travis_py2.6_rebased
correcting get_spoint in array analysis

also simplifying quite a bit, see #682
correcting get_spoint once again and adding test

* updated references
* simplified get_spoint even further
* added docstring
* avoiding some numpy 2.8 warnings in array_analysis
see #682
Merge pull request #682 from mbyt/682

Bug in in array_processing, modul get_spoint
finally working setup.py for windows (importing libtau via ctypes +
small wrapper in obspy/lib/__init__.py)
docs: add readEvents() to core overview
Merge pull request #681 from megies/travis_py2.6_rebased

test travis on py2.6 too
travis: install dependencies from wheelhouse
travis: stay in correct dir