refactor: separate listener acquisition from sync operation

Fix #56 sending large files causes memory overflow

Simplified transport.Buffers now is the alias of net.Buffers

Fix cache missing in writeOnce

Reduce object pool overhead

Use buffered channel instead of RingBuffer

Close connection when the creation of the transport failure

Add pool/pbuffer package to reuse *bytes.Buffer

Add WithChannelHolder support

Support writeForever flags on NewAsyncWriteChannel