NetSSL_Win: TLS handshake may fail for non-blocking sockets

[obiltschnig]

The implementation of the TLS handshake in NetSSL_Win may fail with non-blocking sockets as a negative return value from receiveBytes() or a short write is not properly handled. May require rewrite of the entire handshaking code (state machine).

Furthermore, the state machine may block for up to 200 ms at a time due to a call to select(). This is not acceptable for non-blocking code.