Display abstract classes problems solved

- Linker finds display functions
- .cpp files for display classes deleted
- functions definitions must be in .h file for display classes
- SingleDataKeeper includes specified better
GameHolder class

- GameHolder class added
- ChampionFactory added [NEEDS IMPLEMENTATION]
- Champion deletion prevention while displaying his death
- Champion::Attack should be reworked to keep Command pattern
- Muiltithreading & Teams classes have to be tested
- Teams classes added
- Autogenerating team should generate random members when receiving list
of Champion presets
- Added AliveEnemiesFilter to unlock them from hitting while dead
- SingleDataKeeper is thread-safe no more
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