2.7.0 using optional JIT compilation with numba (#52)
* Create numba_replacements.py
* add numba functionality
* njit for some functions
* Create poetry.lock
* compiled reps n distances fct
* tox numba envs
* JIT inside polygon
* tox skip missing interpreters
* remove redundant fct
* Update utils.py
* typeof numba replacement
* JIT extremity mask
* extremity indices as ndarray
* refactor compile polygon data
* factor out reps n distances dict
* reps_n_distance function
* remove reps n distances impl
* extract numba utils
* Update test_find_visible.py
* Update 0_getting_started.rst
* bump version 2.7.0
* Update README.rst
* Update CHANGELOG.rst
