Pasaeta de "include-what-you-use" per arreglar els includes

Renombrats alguns fitxers per consistencia

source/background.cpp

@@ -1,5 +1,13 @@
 #include "background.h"
-#include "param.h"
+#include <SDL2/SDL_blendmode.h>  // for SDL_BLENDMODE_BLEND
+#include <SDL2/SDL_pixels.h>     // for SDL_PIXELFORMAT_RGBA8888
+#include <algorithm>             // for max, min
+#include <string>                // for basic_string
+#include "asset.h"               // for Asset
+#include "moving_sprite.h"        // for MovingSprite
+#include "param.h"               // for param
+#include "sprite.h"              // for Sprite
+#include "texture.h"             // for Texture
 
 // Constructor
 Background::Background(SDL_Renderer *renderer)