Example Collector: Use class/function attributes instead of encoding information in name

[kfischer-okarin]

I added a little decorator that can be used by the node transformer to add arbitrary attributes to the generated functions and classes.

Using this decorator I moved all the relevant information about the generated examples and groups into attributes of the class/function instead of encoding it in the name.

The introduced attributes are:

• _example: True when the method is an example
• _example_group: True when the class is an example group
• _pending: True when the example or group is pending
• _tags: List of tags
• _example_name: Description of the example/group, which can now directly be used by the formatter without first having to remove underbars etc.

[kfischer-okarin]

Oh, seems the build failed for pypy. I have to look into that later....

[kfischer-okarin]

Seems the pypy compile function is very strict about not specified line arguments of Expressions

[nestorsalceda]

Woah!!

That's an awesome work!

Thanks for contributing, it will land in next release :)