Add 'pickup_stolen' option

Add pickup_stolen option to autopick items stolen from you by a nymph or
monkey, even if they don't match your normal autopickup settings.
Replace was_dropped, was_thrown with a 2-bit bitfield that can contain
values LOST_DROPPED, LOST_THROWN, and LOST_STOLEN (or 0), since they
should all be mutually exclusive anyway as they track the most recent
way the item left the hero's inventory.

[Rebase/merge conflict fixed up.  PR]

src/options.c

@@ -8594,6 +8594,7 @@ doset_simple_menu(void)
                spelling of their names; emphasize what it means */
             if (allopt[i].idx == opt_pickup_types
                 || allopt[i].idx == opt_pickup_thrown
+                || allopt[i].idx == opt_pickup_stolen
                 || allopt[i].idx == opt_dropped_nopick)
                 Strcat(buf, "  (for autopickup)");
             add_menu(tmpwin, &nul_glyphinfo, &any, 0, 0,