These are the bare minimum set of APIs for future new topogical naming
feature (see [here](https://git.io/fj6hy) for a overview of the new
APIs).
These APIs are added early to avoid too much code change for the new
features introduced in the current patch set.
At the moment many feature classes lack of the mustExecute() method and thus can cause a touched feature not to be recomputed and causes the feature to be in a broken state.
Now this new enum value virtually makes the mustExecute() superfluous and thus guarantees to recompute a feature if a modified property has not set the Prop_NoRecompute flag.
On the other hand there are properties that should only touch a feature but not enforce a recompute. This guarantees a better performance and avoids unnecessary recomputes.
For example this is useful for placements where a change can be applied on-the-fly and the feature is up-to-date. Other features that depend on the touched feature will still be recomputed.
fix inheritance of MeshFeaturePy
fix inheritance of PartFeaturePy
remove useless test() method
implement getPyObject in GeoFeature in case a sub-class doesn't implement it
