Dev 1.5.1

[BDonnot]

[FIXED]: Issue #187 : improve the computation and the
documentation of the RedispReward. This has an impact on the env.reward_range of all environments using this
reward, because the old "reward_max" was not correct.
[FIXED] Issue #181 : now environment can be created with
a layout and a warning is issued in this case.
[FIXED] Issue #180 : it is now possible to set the thermal
limit with a dictionary
[FIXED] a typo that would cause the attack to be discarded in the runner in some cases (cases for now not used)
[FIXED] an issue linked to the transformation into gym box space for some environments,
this might be linked to Issue #185
[ADDED] a feature to retrieve the voltage angle (theta) in the backend (backend.get_theta) and in the observation.
[ADDED] support for multimix in the GymEnv (lack of support spotted thanks to Issue #185)
[ADDED] basic documentation of the environment available.
[ADDED] Issue #166: support for simulate in multi environment
settings.
[IMPROVED] extra layer of security preventing modification of observation_space and action_space of environment
[IMPROVED] better handling of dynamically generated classes
[IMPROVED] the documentation of the opponent