Allow dropping just picked up items

When using a menu to drop or put in items into a container,
allow putting in the item (or items) you picked up previously,
by selecting the 'P' entry from the item class menu

Inspired by the itemcat patch by Stanislav Traykov.

Invalidates saves and bones.

include/decl.h

@@ -1094,6 +1094,8 @@ struct instance_globals {
     boolean class_filter;
     boolean bucx_filter;
     boolean shop_filter;
+    boolean picked_filter;
+    boolean loot_reset_justpicked;
 
     /* pline.c */
     unsigned pline_flags;