This interface defines the SILC Client Library API for the application.
 The client operations are defined first.  These are callback functions that
 the application MUST implement since the library may call the functions
 at any time.  At the end of file is the API for the application that
 it can use from the library.  This is the only file that the application
 may include from the SIlC Client Library.

 o SILC Client Operations

   These functions must be implemented by the application calling the SILC
   client library. The client library can call these functions at any time.

   To use this structure: define a static SilcClientOperations variable,
   fill it and pass its pointer to silc_client_alloc function.

 o SILC Client Library API

   This is the API that is published by the SILC Client Library for the
   applications.  These functions are implemented in the SILC Client Library.
   Application may freely call these functions from the library.