Allow partial output struct initialization

[tmteam]

class Car{
	public int Power {get;set;}
	public string Name {get;set;}
	public int Year {get;set;}
}

var result = Funny.Calc<Car>("{ power = 120 }");// Name and Year are not initalized

the problem is that if we got two types:

car1: {power:int, name:text, year:int}

car2: {power:int}

then car1 is convertable to car2

but that feature allows to convert car2 to car1

Solution:

make special property 'default' for fields

then, for output struct type we may say that all the fields are has this property:

car3: {@optional power:int,@optional  name:text,@optional year:int}

the question is - what is lca for car3, car2?

lca(car3, car2) = {power:int,@optional  name:text,@optional year:int}  #???