Chainsaw: Chat message for 'aborted by safe cut'

This provides a feedback to the player.

technic/tools/chainsaw.lua

@@ -128,6 +128,7 @@ local function dig_recursive(x, y, z)
 	if safe_cut and cutter.param2[i] ~= 0 then
 		-- Do not dig manually placed nodes
 		-- Problem: moretrees' generated jungle trees use param2 = 2
+		cutter.stopped_by_safe_cut = true
 		return
 	end
 
@@ -201,6 +202,11 @@ local function chainsaw_dig(player, pos, remaining_charge)
 		return
 	end
 
+	if cutter.stopped_by_safe_cut then
+		minetest.chat_send_player(player_name, S("The chainsaw could not dig all nodes" ..
+			" because the safety mechanism was activated."))
+	end
+
 	minetest.sound_play("chainsaw", {
 		pos = pos,
 		gain = 1.0,