refactor chat history to allow scrolling

src/toxic_strings.h

@@ -48,11 +48,6 @@ void reset_buf(wchar_t *buf, size_t *pos, size_t *len);
    Returns the difference between the old len and new len of buf on success, -1 if error */
 int complete_line(wchar_t *buf, size_t *pos, size_t *len, const void *list, int n_items, int size);
 
-enum {
-    LN_HIST_MV_UP,
-    LN_HIST_MV_DWN,
-};
-
 /* adds a line to the ln_history buffer at hst_pos and sets hst_pos to last history item. */
 void add_line_to_hist(const wchar_t *buf, size_t len, wchar_t (*hst)[MAX_STR_SIZE], int *hst_tot, 
                       int *hst_pos);