Treedb

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Add support for the new optional core `timespan` field.

Add new test flags: ``--glottolog-repo-root`` and ``--force-rebuild``.

Extend tests and integrate with Travis and Codevov.

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Insert languoids in ``id`` order if possible.

Gzip dump-like csv files per default (bump csv23 to 0.3+).

Change default name of ``treedb.write_csv`` to ``treedb.query.csv.

Register ``pandas`` as optional dependency.

Fix xenial compat. Fix Python 3.6 compat.

Fix re-load with ``exclude_raw``.

Improve logging.

Increase test coverage. Log ``sqlite_version()``.

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Add ``treedb.checkout_or_clone()``.

Add ``treedb.print_query_sql(pretty=True)`` formatting with ``sqlparse`` if
importable (``pip install treedb[pretty]`` to include it).

Improve query readability by adding unique labels.

Move recurse condition for ``Languoid.tree()`` from whereclause to join.

Add tests using ``pytest``.

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Add ``example`` view with ``treedb.get_query()``.

Reorganized ``treedb.load()`` to better support repeated changes to
``exclude_views``.

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Add ``roots`` (top-level languoids) count to ``treedb.print_languoid_stats()``.

Gzip-compress `treedb.dump_sql()` by default.

Fix reference to old license.

Add ``raw=False`` to ``treedb.write_json_query_csv()``.

Update documentation.

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Add ``stats`` and ``path_json`` SQL views.

Extend formatting of ``treedb.print_languoid_stats()`` and warn in case of
inconsistencies.

Fix ``Languoid.tree(include_self=False)``.

Add names to query aliases for better SQL output.