tweaks: reduce duplicate code in new_magicline() and move_to_filestruct()

These two functions unnecessarily copy make_new_node(); use that instead.

src/nano.c

@@ -353,14 +353,10 @@ void move_to_filestruct(filestruct **file_top, filestruct **file_bot,
     }
 
     /* Since the text has now been saved, remove it from the filestruct. */
-    openfile->fileage = (filestruct *)nmalloc(sizeof(filestruct));
+    openfile->fileage = make_new_node(NULL);
     openfile->fileage->data = mallocstrcpy(NULL, "");
     openfile->filebot = openfile->fileage;
 
-#ifndef DISABLE_COLOR
-    openfile->fileage->multidata = NULL;
-#endif
-
     /* Restore the current line and cursor position.  If the mark begins
      * inside the partition, set the beginning of the mark to where the
      * saved text used to start. */

src/utils.c

@@ -530,14 +530,8 @@ size_t strlenpt(const char *text)
 /* Append a new magicline to filebot. */
 void new_magicline(void)
 {
-    openfile->filebot->next = (filestruct *)nmalloc(sizeof(filestruct));
+    openfile->filebot->next = make_new_node(openfile->filebot);
     openfile->filebot->next->data = mallocstrcpy(NULL, "");
-    openfile->filebot->next->prev = openfile->filebot;
-    openfile->filebot->next->next = NULL;
-    openfile->filebot->next->lineno = openfile->filebot->lineno + 1;
-#ifndef DISABLE_COLOR
-    openfile->filebot->next->multidata = NULL;
-#endif
     openfile->filebot = openfile->filebot->next;
     openfile->totsize++;
 }