Ontosample

When trying to use ontosample in ontolearn we found that there are some compatibility issues because classes of `ontolearn_light` are not recognized as classes of `ontolearn`.

That is why in this release we made `ontolearn` related imports of `ontosample` conditional, based on the presence of `ontolearn` package. This way, when both packages are installed at the same environment, `ontosample` will use `ontolearn` module and not `ontolearn_light`.

In case of any issue please reach us on the [*Issues*](https://github.com/alkidbaci/OntoSample/issues) tab.

Happy to share the new release of Ontosample.

We got some important changes to the base structure this time. The logic of the samplers stays unchanged.
The following changes were made:

- All the generated knowledge bases/ontologies point to different worlds and no longer conflict with each other.
- Because of that a sampler object can now be reused to perform multiple samples on the initial knowledge base.
- The `save_sample` method now is static and takes 2 arguments: `kb` the sampled knowledge base that you want to save and `filename` the name of the file that will store the ontology (the file will be created at runtime if it does not exist).
- `ontolearn` module renamed to `ontolearn_light` so it does not conflict with the main ontolearn package.
- Updated `ontolearn_light` sub modules with recent changes from main ontolearn package where triplestore logic is removed (a triple store knowledge base is not able to be sampled anyway because it stored in a server).
- Removed methods `get_sampled_nodes` (can use `sampled_kb.individuals_count()` instead).
- `get_removed_nodes` is now renamed to `_get_removed_nodes` indicating that is only for internal usage. Removed individuals can be retrieved as follows:

removed_individuals = set(kb.individuals()) - set(sampled_kb.individuals())


As always you can use `pip install ontosample` to get the lates version via the Python Package index.

Don't hesitate to open an issue in case you are having a problem or you just want to suggest something.

**Full Changelog**: https://github.com/alkidbaci/OntoSample/compare/v0.1.1...v0.2.0

We are happy to announce the first release of **_ontosample_**.

You can now use `pip install ontosample` to get it via the _Python Package index_.

Changes since the initialization commit:

- We are keeping only the **_ontolearn_** files that are necessary to make the sampling work. Everything else is removed from _ontolearn_ module.
- Refactored the code of samplers, now the code is more compact and they are divided in three modules:
- `classic_samplers.py`
- `lpc_samplers.py`
- `lpf_samplers.py`

Note: If you want to try concept learning algorithms of _ontolearn_, you have to install the whole [ontolearn](https://github.com/dice-group/Ontolearn/tree/develop) package because _ontosample_ is using a light version of it.