Release v0.8.1

• [FIXED] a bug with shunts when nb_busbar_per_sub >= 2
• [FIXED] some bugs preventing backward compatibility
• [FIXED] an issue in the computation of gen_q when intialized with pypowsybl
  (some overflow cpp side leading to infinite number in gen_q)
• [FIXED] a bug in the "containers" cpp side (wrong bus was assigned)
  when elements was disconnected, which lead to wrong computations for
  time series or contingency analysis.
• [FIXED] another bug in ContingencyAnalysis (cpp side) leading to wrong computation
  when a powerline was disconnected
• [FIXED] some broken imports when grid2op was not installed
• [FIXED] missing "typing_extension" as required when installation
• [ADDED] some information of compilation directly in the cpp module
• [ADDED] some information of compilation available in the python compilation_options
  module python side
• [ADDED] some convenient methods for ContingencyAnalysis python side (most
  notably the possibility to initialize it from a LightSimBackend and to
  change the topology of the grid)
• [ADDED] a "reward" module in lightsim2grid with custom reward
  based on lightsim2grid.
• [ADDED] a class N1ContingencyReward that can leverage lightsim2grid to
  assess the number of safe / unsafe N-1.
• [IMPROVED] time measurments in python and c++
• [IMPROVED] now test lightsim2grid with oldest grid2op version
• [IMPROVED] speed, by accelerating the reading back of the data (now read only once and then
  pointers are re used)
• [IMPROVED] c++ side avoid allocating memory (which allow to gain speed python side too)
• [IMPROVED] type hinting in LightSimBackend for all 'public' methods (most
  notably the one used by grid2op)
• [IMPROVED] now the benchmarks are more verbose (detailing some compilation options)