264 fixed examples branch 2

Closes #264

See merge request flatland/flatland!251

Merge branch '264_fixed_examples_branch_2' of gitlab.aicrowd.com:flatland/flatland into 264_fixing_examples

reverted all the versioning problems

Merge branch '264_fixed_examples_branch_2' of gitlab.aicrowd.com:flatland/flatland into 264_fixing_examples

# Conflicts:
#	examples/complex_rail_benchmark.py
#	examples/custom_observation_example_02_SingleAgentNavigationObs.py

updated to newest master branch

# Conflicts:
#	flatland/envs/rail_env.py

# Conflicts:
#   flatland/envs/rail_env.py

196 comparison with 0

Closes #198

See merge request flatland/flatland!244

Fixes the examples

Fixes the examples

Refactored: Added function to check if action is required

add agents position numpy matrix in RailEnv in order to speed up the cell_free check (#259)

Closes #259

See merge request flatland/flatland!248

Merge branch 'master' of gitlab.aicrowd.com:flatland/flatland into 259-reduce-computational-complexity-of-env-step

# Conflicts:
#	flatland/envs/rail_env.py

updated tree obs to not do computations for each agent every time again

Closes #260

See merge request flatland/flatland!243

Merge branch 'master' of gitlab.aicrowd.com:flatland/flatland into 259-reduce-computational-complexity-of-env-step

# Conflicts:
#	flatland/envs/rail_env.py

Added Docstring

See merge request flatland/flatland!247

Fixed how we handle agents off the grid with the observation example

Update README.md

See merge request flatland/flatland!242

This closes #198

Redis opts

See merge request flatland/flatland!239

# Conflicts:
#   flatland/envs/rail_env.py