Tag/MultiTag: add (retrieve_)feature_data
Merge pull request #94 from jgrewe/tutorial

more tutorial work...

sweet!
[test] test for multi_tag.retrieve_feature_data
[test] add test for tag.retrieve_feature_data.
Merge pull request #96 from jgrewe/tutorial

some more tutorial work... 

Awesome
Merge pull request #95 from jgrewe/retrieve_feature_data

Retrieve feature data

Cool!
Merge pull request #98 from jgrewe/tutorial

Aaawesome
Update README.md
[tutorial] more introductory words to Features
[tutorial] add untagged example code
[tutorial] add untagged example to tutorial.rst