Free-form properties for all resources and components.
+ Add property and property-storage classes. + Eliminate duplicate floating-point storage in smtk::model. + Eliminate `smtk/model/FloatData.h`. These types have moved to `smtk/resource/PropertyType.h`. + Eliminate m_floatData in smtk::model::Resource and methods that provided access. The new methods for accessing property are available on a per-entity basis in smtk::model::EntityRef. + Move SetProperty operation from model to operation directory/namespace.