some liquid tweaks

minetest.conf.example

@@ -119,8 +119,8 @@
 #motd = Welcome to this awesome Minetest server!
 # Maximum number of players connected simultaneously
 #max_users = 20
-# Set to false to allow old clients to connect
-#strict_protocol_version_checking = true
+# Set to true to prevent old clients connecting
+#strict_protocol_version_checking = false
 # Set to true to enable creative mode (unlimited inventory)
 #creative_mode = false
 # Enable players getting damage and dying

src/client.cpp

@@ -434,7 +434,7 @@ void Client::step(float dtime)
 			snprintf((char*)&data[23], PASSWORD_SIZE, "%s", m_password.c_str());
 
 			// This should be incremented in each version
-			writeU16(&data[51], 3);
+			writeU16(&data[51], PROTOCOL_VERSION);
 
 			// Send as unreliable
 			Send(0, data, false);

src/content_mapnode.cpp

@@ -2269,6 +2269,7 @@ void content_mapnode_init()
 	f->description = std::string("Water");
 	f->setInventoryTextureCube("water.png", "water.png", "water.png");
 	f->param_type = CPT_LIGHT;
+	f->param2_type = CPT_LIQUID;
 	f->draw_type = CDT_LIQUID;
 	f->light_propagates = true;
 	f->solidness = 0; // Drawn separately, makes no faces
@@ -2334,6 +2335,7 @@ void content_mapnode_init()
 #endif
 	}
 	f->param_type = CPT_LIGHT;
+	f->param2_type = CPT_LIQUID;
 	f->draw_type = CDT_LIQUID_SOURCE;
 	f->light_propagates = true;
 	f->walkable = false;
@@ -2372,6 +2374,7 @@ void content_mapnode_init()
 	f->setInventoryTextureCube("lava.png", "lava.png", "lava.png");
 	f->used_texturenames["lava.png"] = true;
 	f->param_type = CPT_LIGHT;
+	f->param2_type = CPT_LIQUID;
 	f->draw_type = CDT_LIQUID;
 	f->light_propagates = false;
 	f->light_source = LIGHT_MAX-1;
@@ -2437,6 +2440,7 @@ void content_mapnode_init()
 #endif
 	}
 	f->param_type = CPT_LIGHT;
+	f->param2_type = CPT_LIQUID;
 	f->draw_type = CDT_LIQUID_SOURCE;
 	f->light_propagates = false;
 	f->light_source = LIGHT_MAX-1;

src/defaultsettings.cpp

@@ -86,7 +86,7 @@ void set_default_settings(Settings *settings)
 	// "map-dir" doesn't exist by default.
 	settings->setDefault("motd", "");
 	settings->setDefault("max_users", "20");
-	settings->setDefault("strict_protocol_version_checking", "true");
+	settings->setDefault("strict_protocol_version_checking", "false");
 	settings->setDefault("creative_mode", "false");
 	settings->setDefault("enable_damage", "true");
 	settings->setDefault("only_peaceful_mobs", "false");

src/map.cpp

@@ -1614,21 +1614,21 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 		u8 liquid_kind = CONTENT_IGNORE;
 		LiquidType liquid_type = content_features(n0.getContent()).liquid_type;
 		switch (liquid_type) {
-			case LIQUID_SOURCE:
-				liquid_level = LIQUID_LEVEL_SOURCE;
-				liquid_kind = content_features(n0.getContent()).liquid_alternative_flowing;
-				break;
-			case LIQUID_FLOWING:
-				liquid_level = (n0.param2 & LIQUID_LEVEL_MASK);
-				liquid_kind = n0.getContent();
-				break;
-			case LIQUID_NONE:
-				// if this is an air node, it *could* be transformed into a liquid. otherwise,
-				// continue with the next node.
-				if (n0.getContent() != CONTENT_AIR)
-					continue;
-				liquid_kind = CONTENT_AIR;
-				break;
+		case LIQUID_SOURCE:
+			liquid_level = LIQUID_LEVEL_SOURCE;
+			liquid_kind = content_features(n0.getContent()).liquid_alternative_flowing;
+			break;
+		case LIQUID_FLOWING:
+			liquid_level = (n0.param2 & LIQUID_LEVEL_MASK);
+			liquid_kind = n0.getContent();
+			break;
+		case LIQUID_NONE:
+			// if this is an air node, it *could* be transformed into a liquid. otherwise,
+			// continue with the next node.
+			if (n0.getContent() != CONTENT_AIR)
+				continue;
+			liquid_kind = CONTENT_AIR;
+			break;
 		}
 
 		/*
@@ -1669,6 +1669,9 @@ void Map::transformLiquids(core::map<v3s16, MapBlock*> & modified_blocks)
 						if (nb.t == NEIGHBOR_LOWER) {
 							flowing_down = true;
 						}
+					}else if (nb.t == NEIGHBOR_LOWER && nb.n.getContent() == CONTENT_IGNORE) {
+						flowing_down = true;
+						neutrals[num_neutrals++] = nb;
 					} else {
 						neutrals[num_neutrals++] = nb;
 					}

src/mapnode.h

@@ -109,7 +109,8 @@ enum ContentParamType
 	CPT_LIGHT,
 	CPT_MINERAL,
 	// Direction for chests and furnaces and such
-	CPT_FACEDIR_SIMPLE
+	CPT_FACEDIR_SIMPLE,
+	CPT_LIQUID
 };
 
 enum LiquidType