CPC mode 5 : replaced the global Constraint_mode by a state (Image_mode) in each versioned T_Page: This allows keeping it sane when swapping to Spare, and when Undo/Redoing. Also fixed the first page when program starts, it was unnecessarily allocating pointers for the maximum number of layers(16)/frames(999)

git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@1907 416bcca6-2ee7-4201-b75f-2eb2f807beb1

src/struct.h

@@ -401,6 +401,8 @@ typedef struct T_Page
   int       Height;  ///< Image height in pixels.
   T_Palette Palette; ///< Image palette.
 
+  byte      Image_mode; ///< 0= layered image, 1=animation,
+
   char      Comment[COMMENT_SIZE+1]; ///< Comment to store in the image file.
 
   char      File_directory[MAX_PATH_CHARACTERS];///< Directory that contains the file.