core.cc: slightly enhanced bindings for Property

Just for better testing of the Section bindings
PySection: property for Properties
PySection: property with name and inherited props

- Method has_property_with_name and get_property_with_name
- Hidden method _inherited_properties
- Some TODOs for fututre features
- Tests
Merge pull request #10 from stoewer/metadata

Bindings for Section complete for now

LGTM