tweaks: split the grafting code off from copy_from_buffer()

Later on we're going to need the ability to graft a buffer into the
current file buffer without making a copy of it first.

src/nano.c

@@ -392,9 +392,9 @@ void extract_buffer(filestruct **file_top, filestruct **file_bot,
 	new_magicline();
 }
 
-/* Copy all text from the given filestruct to the current filestruct
+/* Meld the given buffer into the current file buffer
  * at the current cursor position. */
-void copy_from_buffer(filestruct *somebuffer)
+void ingraft_buffer(filestruct *somebuffer)
 {
     filestruct *top_save;
     size_t current_x_save = openfile->current_x;
@@ -427,8 +427,8 @@ void copy_from_buffer(filestruct *somebuffer)
     free_filestruct(openfile->fileage);
 
     /* Put the top and bottom of the current filestruct at the top and
-     * bottom of a copy of the passed buffer. */
-    openfile->fileage = copy_filestruct(somebuffer);
+     * bottom of the passed buffer. */
+    openfile->fileage = somebuffer;
     openfile->filebot = openfile->fileage;
     while (openfile->filebot->next != NULL)
 	openfile->filebot = openfile->filebot->next;
@@ -484,6 +484,14 @@ void copy_from_buffer(filestruct *somebuffer)
 	new_magicline();
 }
 
+/* Meld a copy of the given buffer into the current file buffer. */
+void copy_from_buffer(filestruct *somebuffer)
+{
+    filestruct *the_copy = copy_filestruct(somebuffer);
+
+    ingraft_buffer(the_copy);
+}
+
 /* Create a new openfilestruct node. */
 openfilestruct *make_new_opennode(void)
 {

src/proto.h

@@ -432,6 +432,7 @@ partition *partition_filestruct(filestruct *top, size_t top_x,
 void unpartition_filestruct(partition **p);
 void extract_buffer(filestruct **file_top, filestruct **file_bot,
 	filestruct *top, size_t top_x, filestruct *bot, size_t bot_x);
+void ingraft_buffer(filestruct *somebuffer);
 void copy_from_buffer(filestruct *somebuffer);
 openfilestruct *make_new_opennode(void);
 void unlink_opennode(openfilestruct *fileptr);