Better reporting directions for impossible()

Rather than just informing the player that saving and reloading might
fix the problem, they are now encouraged to report the problem to the
value of DEVTEAM_EMAIL. If the sysconf specifies SUPPORT, that is also
presented as an option.

src/pline.c

@@ -481,6 +481,10 @@ VA_DECL(const char *, s)
     if (g.program_state.something_worth_saving)
         Strcat(pbuf, "  (Saving and reloading may fix this problem.)");
     pline("%s", VA_PASS1(pbuf));
+    pline("Please report these messages to %s.", DEVTEAM_EMAIL);
+    if (sysopt.support) {
+        pline("Alternatively, contact local support: %s", sysopt.support);
+    }
 
     g.program_state.in_impossible = 0;
     VA_END();