Migrated the whole main loop

The main loop of the game is now contained in Plansza class

headers/AudioManager.h

@@ -7,6 +7,7 @@
 
 class AudioManager {
 public:
+    AudioManager() = default;
     bool loadBackgroundMusic(const std::string& filePath);
     void playBackgroundMusic(float volume = 50.f, bool loop = true);
     void stopBackgroundMusic();

headers/Plansza.h

@@ -15,8 +15,7 @@
 
 class Plansza {
 public:
-    Plansza(unsigned int windowHeight, unsigned int windowWidth);
-    Plansza(unsigned int windowHeight, unsigned int windowWidth, sf::RenderWindow *mainWindow);
+    Plansza(unsigned int windowHeight,unsigned int windowWidth, sf::RenderWindow *mainWindow);
     Size getSize();
     std::vector<Meteor> &getMeteors();
     void spawn_meteor();