Immutable struct with getter macro

We can use the getter macro to create getters to all of the attributes.

• macros on Object

struct Person
  getter name, email

  def initialize(@name : String, @email : String)
  end
end

foo = Person.new("Foo", "me@foo.bar")
p! foo
p! foo.name
p! foo.email

foo # => Person(@name="Foo", @email="me@foo.bar")
foo.name # => "Foo"
foo.email # => "me@foo.bar"