avoid collections in EXPRESS TYPEs

There are very few TYPEs equivalent to a collection (LIST, ARRAY, SET). Examples are:

```
TYPE IfcArcIndex = LIST [3:3] OF IfcPositiveInteger;
END_TYPE;

TYPE IfcComplexNumber = ARRAY [1:2] OF REAL;
END_TYPE;

TYPE IfcCompoundPlaneAngleMeasure = LIST [3:4] OF INTEGER;
WHERE
MinutesInRange : ABS(SELF[2]) < 60;
SecondsInRange : ABS(SELF[3]) < 60;
MicrosecondsInRange : (SIZEOF(SELF) = 3) OR (ABS(SELF[4]) < 1000000);
ConsistentSign : ((SELF[1] >= 0) AND (SELF[2] >= 0) AND (SELF[3] >= 0) AND ((SIZEOF(SELF) = 3) OR (SELF[4] >= 0)))
OR
((SELF[1] <= 0) AND (SELF[2] <= 0) AND (SELF[3] <= 0) AND ((SIZEOF(SELF) = 3) OR (SELF[4] <= 0)));
END_TYPE;
```

I suggest to encode these differently. As a result, we can likely more easily translate all TYPEs to known datatypes in other languages (e.g. xsd:dateTime, xsd:integer, etc.), rather than having to encode exceptions for these particular cases. Can't we make them ENTITIES with attributes?