fix all ipython notebooks

[karlnapf]

See the logs of our buildbot http://buildbot.shogun-toolbox.org/builders/nightly_default

Search for "error |"

After this, add a github hook, so that buildbot runs notebooks and reports back to github so that we can avoid merging changes that break notebooks. Ping me or @vigsterkr for that

[karlnapf]

@vigsterkr so right now the nightly build is green even though the opencv notebook still fails. I guess in terms of keeping things passing, we should make it fail if a notebook fails, no?

[vigsterkr]

oh damn that generate notebook script needs fixing... as now the codebook generator's return value is shadowed by the png extractor.... hence it became green, since the html extractor runs without errors... and that overwrites the return value :(

[vigsterkr]

ok so this is still lingering around, currently based on the nightly_default the followings are failing:

• Scene_classification.ipynb, it's about OpenCV interface changes... needs updates
• DecisionTrees.ipynb: seems a bit more serious:

SystemError: [ERROR] In file /home/buildslave/nightly_default/build/src/shogun/base/SGObject.cpp line 744: Could not create empty instance of "BinaryTreeMachineNode". The reason for this usually is that get_name() of the class returns something wrong, or that a class has a wrongly set generic type.

• logdet.ipynb: need to switch to python3

[vigsterkr]

as of today these are the currently failing notebooks:

• Scene_classification.ipynb
• DecisionTrees.ipynb
• variational_classifier.ipynb
• Classification.ipynb