[fpc-pascal] Option type

[denisgolovan]

> You need to use a constraint like:
> 
> type
> generic TOption<T: TObject> = record
> case IsSome:boolean of
> true: ( some: T );
> false: ();
> end;
> 
> Not sure why though.
> 
> Regards,
> Ryan Joseph

That would limit supported types to class instances.
I'll like to avoid that. 
Ideally TOption type should allow any type (primitives, strings, objects, class instances, etc).

-- Regards,
Denis Golovan