Reinstate the Shift-Ins paste behaviour, which was accidentally

broken by the mouse button redesignation that came with xterm mouse
reporting.

[originally from svn r1130]

putty.h

@@ -426,6 +426,7 @@ void term_deselect(void);
 void term_update(void);
 void term_invalidate(void);
 void term_blink(int set_cursor);
+void term_do_paste(void);
 void term_paste(void);
 void term_nopaste(void);
 int term_ldisc(int option);