Merge branch 'master' of gitlab.aicrowd.com:flatland/flatland into 64-prediction-should-respect-target

Merge branch 'master' of gitlab.aicrowd.com:flatland/flatland into 64-prediction-should-respect-target

Moved Prediction from Env to Observation. You can now pass your own predictor to the tree observation builder. if no predictor is passed everything stays the same.

added get_many() method to observation builders, base class and derived. Also removed the render() methods in the env base class and railenv

fixed bug for treeobs in curved rails: now the tree branch will look as 'forward' even on a curve

See merge request flatland/flatland!59

Fix43and60

Closes #60

See merge request flatland/flatland!58

Cleanup flake8 once more

See merge request flatland/flatland!56

code cleanup

See merge request flatland/flatland!55

Changed behavior of environment to change action_dict of agents after their input. --> Giacomo please check that this is ok with your implementation

updated observation to cummulate the number of observed agents with same or other direction along each branch