Big follow up of version 1 1

[Necktschnagge]

This is the todo of #158 copied:

TODOs:

• check all test and if there have to be new one for 1_1
• remove friend class declarations whenever possible
• Why does solver1_1 have a class state_path, models1_0 already has one?
• Add a separate class for permutations
• in solver 1 1 fix : // should throw std::unexpected();
• [src/abstract_game_controller.h] missing docstrings
• review and docstrings for
  • solver_environment.h,
  • game_controller.h,
  • game_factory.h missing but ok
• review gui_interactive_controller.h and cpp -> files removed
• svg_1_1 review + doc -> Pedantic Review: svg_1_0 and svg_1_1 #172
• review + doc world_generator 1 1
• dependency diagram: view external headers!

missing tests:

• models 1_1
• solver 1_0
• solver 1_1
• test models 1 0 : inline std::size_t count_changed_pieces(const positions_of_pieces& another)

Feature requests:

• history hover -> preview start configuration of game

Follow-up

• game controller h: todos in comments
• review mainwindow h+cpp
• review original game factory, add some constructors taking group counters on initialisation
• Remove the cyclic group from SpecialCaseGameFactory. just inherit from Abstract Game Controller