DateTime :: dayOfWeek - Get day of week
The function returns the day of week from the date value beginning with 1 for Monday.
Return value:  Day of week ( int32  )
Number of the day in the week (counting from Monday).
Implementation overview
-  - internal feature (not documented)
 DateTime :: dayOfWeek (  )
-  - internal feature (not documented)
 DateTime :: dayOfWeek ( iDayOfWeek )

