use const char* for file names

gframe/image_manager.cpp

@@ -183,7 +183,7 @@ void imageScaleNNAA(irr::video::IImage *src, irr::video::IImage *dest) {
 			dest->setPixel(dx, dy, pxl);
 		}
 }
-irr::video::ITexture* ImageManager::GetTextureFromFile(char* file, s32 width, s32 height) {
+irr::video::ITexture* ImageManager::GetTextureFromFile(const char* file, s32 width, s32 height) {
 	if(mainGame->gameConf.use_image_scale) {
 		irr::video::ITexture* texture;
 		irr::video::IImage* srcimg = driver->createImageFromFile(file);

gframe/image_manager.h

@@ -14,7 +14,7 @@ public:
 	void ClearTexture();
 	void RemoveTexture(int code);
 	void ResizeTexture();
-	irr::video::ITexture* GetTextureFromFile(char* file, s32 width, s32 height);
+	irr::video::ITexture* GetTextureFromFile(const char* file, s32 width, s32 height);
 	irr::video::ITexture* GetTexture(int code, bool fit = false);
 	irr::video::ITexture* GetTextureThumb(int code);
 	irr::video::ITexture* GetTextureField(int code);