* Added a feature to filter out properties that are associated with a particular vertex-/edge-type;
* Added to schema values with sets of pairs (vertex/edge-type, it's properties);
* Added `has` method to vertex/edge types to associate several properties (a type-set) at once;
* Simplified `HasProperty` (removed `SmthHasProperty`, etc.);
* Renamed `HasProperties` trait (about getters) to `CanHaveProperties`;
* Removed right-associative property getter (`ReadFrom`);
* Renamed `AnyProperty.PropertyOf` to `Property.Of`;