Add a scratch buffer to the history ring. (closes #3082)

This patch creates an extra slot in the history ring for a scratch
buffer (at h->last).  If you are editing inside that buffer, it is
preserved when you scroll up/down through the history.  Editing while in
other places in history are *not* preserved with this patch.

Another behavior change worth noting with this patch: the position in
history is now reset to the scratch buffer after each input entry.
Before, the position would be stay wherever it was - you didn't restart
at the "bottom" each time.

1 files changed, 3 insertions, 0 deletions

diff --git a/history.h b/history.h
index 0bd37ddb..994526b6 100644
--- a/history.h
+++ b/history.h
@@ -41,5 +41,8 @@ void mutt_read_histfile(void);
 void mutt_history_add(history_class_t, const char *, int);
 char *mutt_history_next(history_class_t);
 char *mutt_history_prev(history_class_t);
+void mutt_reset_history_state (history_class_t);
+int mutt_history_at_scratch (history_class_t);
+void mutt_history_save_scratch (history_class_t, const char *);
 
 #endif