bugfix load flatland

See merge request flatland/flatland!201

utility for getting entry directions of a cell

See merge request flatland/flatland!199

bugfix create existing folder

See merge request flatland/flatland!200

#80 Why do we not allow actions to change while running in a cell?

See merge request flatland/flatland!198

Merge branch '173-refactoring-type-hints-named-structures-for-observation-builders-and-predictors' into 'master'

Refactoring: add return types for ObservationBuilder.get(self, handle: int =...

Closes #173

See merge request flatland/flatland!196

#186 bugfix next_malfunction below zero

Closes #186

See merge request flatland/flatland!197

Refactoring: add return types for ObservationBuilder.get(self, handle: int = 0) and ObservationBuilder.get_many(self, handles: Optional[List[int]] = None)

Resolve "Test for Multi-Speed"

Closes #163 and #168

See merge request flatland/flatland!194

Merge branch '173-refactoring-type-hints-named-structures-for-observation-builders-and-predictors' into 'master'

Resolve "Refactoring: Type hints/named structures for observation builders and predictors."

See merge request flatland/flatland!195

Resolve "Enhance sparse_rail_generator"

Closes #169

See merge request flatland/flatland!190

Merge branch '169-Enhance_sparse_rail_generator' of gitlab.aicrowd.com:flatland/flatland into 163-multispeed-tests-penalties

Merge branch '169-Enhance_sparse_rail_generator' of gitlab.aicrowd.com:flatland/flatland into 163-multispeed-tests-penalties

Merge branch '169-Enhance_sparse_rail_generator' of gitlab.aicrowd.com:flatland/flatland into 163-multispeed-tests-penalties