In the middle of bugfixing odd buffering issue with rcv_window_buffer
Moves my_ackno++ from rel_recvpkt to rel_output, ensures working rcv_window_buffer, initializes all the .is_full to 0 for the rcv_window_buffer. Needs fix in case ACK sent from rel_output does not survive transmission
All code in one place
Final version, still small error in rcv window buffer with packets' seqno being multiple of window size, but generally good