Upgrade to version 0.1.1: Some improvments for speed and readibility

[0.1.1] - 2022-01-11

[ADDED] a logger in the "Node" and "EnvTree" classes.
[ADDED] a "loading widget" when an assistant is loading (see issue https://github.com/BDonnot/grid2game/issues/38)
[ADDED] a "loading widget" when saving the results (see issue https://github.com/BDonnot/grid2game/issues/39)
[IMPROVED] error are catched when an assistant raises some when ask to perform an action.
[IMPROVED] progress bar updates during computation (even if nothing else does)
[IMPROVED] illegal actions are now displayed on the GUI (see https://github.com/BDonnot/grid2game/issues/3)
[IMPROVED] when creating a topological action, the graph of the substation is updated "on the fly" (see https://github.com/BDonnot/grid2game/issues/36)
[IMPROVED] buses having 2 or more activated buses are displayed in a different color (see https://github.com/BDonnot/grid2game/issues/35)
[IMPROVED] positionning of the elements (all rounding are remove, which makes things smoother) (see https://github.com/BDonnot/grid2game/issue/43)
[IMPROVED] visualization of parrallel powerlines (see issue see https://github.com/BDonnot/grid2game/issue/42)