Pybgl

* Bug fix
* `GraphView.to_dot` (for empty views)
* Documentation:
* The API pages are now separated
* Fixed documentation build
* Added `sphinx_copybutton`

* Improved documentation and tests.
* Fixed docstrings
* Improved `developers.md`
* The package now exposes the following symbols:
* Automaton: `BOTTOM`, `EPSILON`
* Graphviz: `ReadGraphvizVisitor`, `read_graphviz`
* Heap: `compare_to_key`
* Regexp: `MAP_OPERATORS_ALG`, `MAP_OPERATORS_RE`, `RpnDequeAlg`, `RpnDequeAst`, `re_escape`
* Bug fixes:
* `read_graphviz`;
* `write_graphviz`;
* `Trie.__init__` (kwargs forwarding).
* Fixed `make_automaton`
* Flake8 tests/
* API changes:
* Renamed `make_path` to `make_shortest_path`
* Renamed `make_dag` to `make_shortest_paths_dag`
* `make_incidence_node_automaton` and `make_node_automaton` now accept `pmap_vlabel=None`
* Renamed attributes prefixed by `m_` and remove the corresponding properties.
* Cleaned the `revuz_minimize` function.
* Improved the `make_*automaton` functions.
* Renamed constructor argument to `Constructor`.
* Bug fix for the empty automaton.
* `pmap_vlabel` is now optional.
* Reverted from `poetry-bumpversion` to `bumpversion` (installation issues under debian).

* Migrated from `bumpversion` to `poetry-bumpversion`.

* Migrated sphinx theme to pydata.
* Improved documentation, code style, `flake8` errors.
* Exposed some missing classes:
* `DirectedGraph`;
* `UndirectedGraph`;
* `dotstr_to_html`;
* `enrich_kwargs`;
* `run_graphviz`;
* `make_node_automaton`.
* Bug fix `*_copy`, `GraphView.*_degree`.
* The Graphviz-related function now correctly forward the kwargs arguments (e.g. `engine=`):
* `ipynb_display_graph`;
* `graph_to_html`;
* `dotstr_to_html`;
* `write_graphviz`;
* `run_graphviz`.
* `pybgl.AssocPropertyMap` can now only wrap a `defaultdict` (not a `dict`).

* Added many language theory data structures and algorithms.
* Enabled CI.
* Improved documentation and tests.
* Improved code style (`flake8`).
* Progessively removing graph primitives function to remove every `import *`.

* Added many graph structures and algorithms.