WebSocket module now uses wslay library.

Both client and server are supported on native builds (as usual).

SSL server is still not supported, but will soon be possible with this
new library.

The API stays the same, we just need to work out potential issues due to
this big library switch.

core/io/stream_peer_tcp.cpp

@@ -217,6 +217,11 @@ Error StreamPeerTCP::read(uint8_t *p_buffer, int p_bytes, int &r_received, bool
 
 			to_read -= read;
 			total_read += read;
+
+			if (!p_block) {
+				r_received = total_read;
+				return OK;
+			}
 		}
 	}