Patch from Egmont Koblinger to implement two extended variants of

xterm mouse tracking, both supported by the current up-to-date xterm
(288). They take the form of two new DEC terminal modes, 1006 and
1015, which do not in themselves _enable_ mouse tracking but they
modify the escape sequences sent if mouse tracking is enabled in the
usual way.

[originally from svn r9752]

terminal.h

@@ -152,6 +152,8 @@ struct terminal_tag {
     int big_cursor;
 
     int xterm_mouse;		       /* send mouse messages to host */
+    int xterm_extended_mouse;
+    int urxvt_extended_mouse;
     int mouse_is_down;		       /* used while tracking mouse buttons */
 
     int bracketed_paste;