Return the number of days in a month
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 Syntax

        GT_DaysInMonth( dDate )

 Arguments:

      dDate - Date to be considered

 Returns:

      Number of days in given month

 Description:

      Returns the number of days in a month

 Examples:

      Find the last day in February 1993 :

          nDay := GT_DaysInMonth( CTOD( "01/02/93" ) )

 Source: DAYSMONT.PRG

 Author:  Martin Colloby