Fix client disconnect from leftover socket recv timeout

Clear the 5-second SO_RCVTIMEO that was set during the connection
handshake but never removed. The timeout persisted into the game
session, causing the client to disconnect whenever the server paused
for longer than 5 seconds (e.g. autosave, chunk I/O).

Also update README with chunk unloading and connection stability fixes.

Minecraft.Client/ServerChunkCache.cpp

@@ -927,6 +927,7 @@ bool ServerChunkCache::tick()
 						int ix = chunk->x + XZOFFSET;
 						int iz = chunk->z + XZOFFSET;
 						int idx = ix * XZSIZE + iz;
+						delete m_unloadedCache[idx];
 						m_unloadedCache[idx] = chunk;
 						cache[idx] = nullptr;
 					}

Minecraft.Client/Windows64/Network/WinsockNetLayer.cpp

@@ -455,6 +455,12 @@ bool WinsockNetLayer::JoinGame(const char* ip, int port)
 	{
 		return false;
 	}
+
+	// Clear the recv timeout now that the handshake is complete.
+	// The recv thread should block indefinitely waiting for data.
+	DWORD noTimeout = 0;
+	setsockopt(s_hostConnectionSocket, SOL_SOCKET, SO_RCVTIMEO, (const char*)&noTimeout, sizeof(noTimeout));
+
 	s_localSmallId = assignedSmallId;
 
 	// Save the host IP and port so JoinSplitScreen can connect to the same host