adding support to the 700GB tape

VC6->VC7 port (VC7 already defined BYTE, SHORT, LONG + I don't know why but QUAD structure does not compile using a LONG on VC7 - but compiled with 'int'...)

Enclose defintions of INVALID_SOCKET, SOCKET_ERROR, closesocket, ioctlsocket between #ifndef/#endif (they are coming from _WIN32 and CASTOR is not the only package trying to mimic _WIN32 with #define hacks - an example is gsoap and its redefinition of closesocket [btw gsoap should have protected his definition as well...])