Add z-index management to HUD

src/hud.cpp

@@ -43,6 +43,8 @@ const struct EnumString es_HudElementStat[] =
 	{HUD_STAT_ALIGN,  "alignment"},
 	{HUD_STAT_OFFSET, "offset"},
 	{HUD_STAT_WORLD_POS, "world_pos"},
+	{HUD_STAT_SIZE,    "size"},
+	{HUD_STAT_Z_INDEX, "z_index"},
 	{0, NULL},
 };