Try to include some more test dependencies in the travis build (but exclude...

Try to include some more test dependencies in the travis build (but exclude them in Py2.6, which is often no longer supported already).

.travis.yml

@@ -38,6 +38,7 @@ branches:
 
 install:
   - python -c 'import sys; print("Python %s" % (sys.version,))'
+  - python -c 'import sys; sys.exit("exclude Py2.6" and sys.version_info >= (2, 7))' || pip install -r test-requirements.txt
   - CFLAGS="-O2 -ggdb -Wall -Wextra $(python -c 'import sys; print("-fno-strict-aliasing" if sys.version_info[0] == 2 else "")')" python setup.py build
 
 before_script: ccache -s

test-requirements.txt

+numpy
+jupyter
+line_profiler
+coverage