Named / Type defined Enums

[ghaith]

Is your feature request related to a problem? Please describe.
The norm supports different datatype for enums, where an enum field behaves as a named value of that datatype.
Example :

TYPE MyInt : INT ( Red := 1, Yellow := 2, Green := 3); END_TYPE
PROGRAM prg
VAR value : MyINT := RED; END_VAR
value := value + 2; //Green
IF value = MyInt#Green THEN
  value := 10; //Outside the enum range but allowed
END_IF

[create-issue-branch]

Branch issue-277-Named_/_Type_defined_Enums created!