updated test to handle new predictor

Added potential conflict to tree observation as an 8th feature. ATTENTION this means that the observation space dimension has increased! will still check that this is handled correctly everywhere but looks good.

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

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

Update split_tree in observations.py to include the agent direction and normalize the state correctly

#56 bugfix wrong length of observation vector; #47 added two flags whether there is another agent on the same position in the same or opposite direction