wrlib: added support for imagemagick third-party lib

It uses to provide some missing common image format
like SVG, BMP, PICT, ...

wrlib/imgformat.h

@@ -39,12 +39,13 @@ typedef enum {
 	IM_PPM     =  4,
 	IM_JPEG    =  5,
 	IM_GIF     =  6,
-	IM_WEBP    =  7
+	IM_WEBP    =  7,
+	IM_MAGICK  =  8
 } WRImgFormat;
 
 /* How many image types we have. */
 /* Increase this when adding new image types! */
-#define IM_TYPES    7
+#define IM_TYPES    8
 
 /*
  * Function for Loading in a specific format
@@ -73,6 +74,10 @@ RImage *RLoadGIF(const char *file, int index);
 RImage *RLoadWEBP(const char *file);
 #endif
 
+#ifdef USE_MAGICK
+RImage *RLoadMagick(const char *file_name);
+#endif
+
 /*
  * Function for Saving in a specific format
  */