Ask user if they are sure that they want to quit
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 Syntax

        H_QuitSystem( lClear )

 Arguments:

      lClear - If .T., clear screen

 Returns:

      .T. if the user does want to quit
      .F. otherwise

 Description:

      Pops up a menu with two options - Yes and No.  If the user selects
      Yes, .T. is returned

 Examples:



 Header File: H_LIB52.CH

 Source: QUITSYS.PRG

 Author:  Martin Colloby