[tutorial] more introductory words to Features
[tutorial] add untagged example code
[tutorial] add untagged example to tutorial.rst
[tutorial] link untagged feature example in tutorial list
[tutorial] change code to use the dataView features in taggedFeature.py
[tutorial] change stimulus retrieval to use retrive_feature_data
[tutorial] add plotting of retrieved roi data
[tutorial] add image for retrieved rois
[tutorial] add text for retrieve data section
[tutorial] separate design principles from tutorials
[tutorial] remove design principles from the tutorials file.
[tutorial] add overview and tutorials as separate points
adapted test cases for the changes in NIX dataAccess api
Merge pull request #99 from jgrewe/tutorial

Tutorial

LGTM
Section: impl. __setitem__ for easy prop creation

This should all creation of properties with s['key'] = value
[test] section[key] = prop tests
Merge pull request #101 from gicmo/section_setitem

that looks damn good to me :-)
Section: expose properties as .props
[test] TestSection: modify to use .props
Section: simplify, i.e. dict like, value access

Provides the value of proprties for Section['prop'] instead
of the Property. Should make it easier to work with odML

Cf issue #102