Finish up singleton refactoring into one giant class

src/singletons/fontmanager.cpp

@@ -32,6 +32,7 @@ FontManager::FontManager()
         this->currentFontByScale.clear();
         this->fontChanged.invoke();
     });
+
     this->currentFontSize.connect([this](const int &newValue, auto) {
         this->incGeneration();
         //        this->currentFont.setSize(newValue);
@@ -40,12 +41,6 @@ FontManager::FontManager()
     });
 }
 
-FontManager &FontManager::getInstance()
-{
-    static FontManager instance;
-    return instance;
-}
-
 QFont &FontManager::getFont(FontManager::Type type, float scale)
 {
     //    return this->currentFont.getFont(type);