Property: remove type (fixes #264)

- Let Property inherit from IEntity instead of INamedEntity
- Redefine attributes name and definition on Property
- Adjust tests
ISection: update documentation comment
Section: creating a property with value
TestSection: c++11 style for loops
DataArray: polynomCoefficients takes a const ref

the setter DataArray::polynomCoefficients was taking a
non const reference to vector<double>.

This commit fixes this issue.
Merge pull request #265 from stoewer/property-type

Property: remove type