Syntax for defining constructors
================================

Syntax option 1:

    # default constructor name should be `new`
    # if omitted, a default constructor should be created (similar to Java)
    constructor
    code
        field = 123
    end

    # name can be overridden
    constructor new_with_value
        int value
    code
        field = value
    end

Syntax option 2:

    func :new
    code
        field = 123
    end

    func :with_value
        int value
    code
        field = value
    end


Other things to decide:

* Should `new` be a keyword or an identifier?
    - An identifier is more logical (because it can be overridden)
    - But a keyword would prevent it from being used as a function,
      field or enum name.
    - Could forbid `new` and `new_`... in other places.
      (It's not just `new` anyway)
* Type-identifiers:
    - `new` and `new_`... could be special and trigger a typeident search?
    - Or maybe just `:xxx`