Move examples/tutorials/tutor.py into traitsui/extras

[shoeb-github]

resolves #620

• Moved the bulk of code in examples/tutorials/tutor.py to traits/extras/tutor.py. Also moved the image resources in examples/tutorials/images to traits/extras/images.
• Added a main function in examples/tutorials/tutor.py that calls the code in traits/extras/tutor.py

[corranwebster]

I can see that you have moved the images, but they are not showing up when installed on OS X:

Looking at the installed files, I think you need to update the setup.py to add the new image directory to the package_data. This can be checked by using etstool to install into a new environment and then running the tutor script.

It is also worth checking that the files are included when you build a source distribution (python setup.py sdist if I remember correctly and then look in the dist subdir).

[shoeb-github]

Thanks for pointing that out. I added the images directory to package_data.

[corranwebster]

LGTM