Fire sources can ignite candles, lamps, and potions of oil

... on the floor, in monster inventory, and in hero's inventory.

Items in your inventory being ignited produce a message even if you're
blind - you can see the lit-state by viewing inventory anyway, so just
give player the message.

(via xNetHack)

include/extern.h

@@ -2715,6 +2715,7 @@ E boolean NDECL(lava_effects);
 E void NDECL(sink_into_lava);
 E void NDECL(sokoban_guilt);
 E const char * FDECL(trapname, (int, BOOLEAN_P));
+E void FDECL(ignite_items, (struct obj *));
 
 /* ### u_init.c ### */