new style for debug information about functions: no more SETFUNCTION

opcodes. When a function is called, its entry in the stack is marked with
LUA_T_(C)MARK, so function 'luaD_stackedfunction' can find it if
needed.
Functions now have their file names in the headers, so there is no need
of 'addfile' and the like.

func.h

@@ -12,6 +12,10 @@ typedef struct TFunc
   char		marked;
   int		size;
   Byte		*code;
+  int		lineDefined;
+  char		*name1;  /* function or method name (or null if main) */
+  char		*name2;  /* object name (or null if not method) */
+  char		*fileName;
 } TFunc;
 
 Long luaI_funccollector (void);