Remove :complex option

It was only needed for my experimental dirty tracking feature which is
no longer part of Virtus

lib/virtus/attribute.rb

@@ -79,7 +79,7 @@ def self.determine_type_from_string(string)
     #
     # @example
     #   Virtus::Attribute::String.options
-    #   # => {:primitive => String, :complex => false}
+    #   # => {:primitive => String}
     #
     # @return [Hash]
     #   a hash of default option values
@@ -98,7 +98,7 @@ def self.options
     #
     # @example
     #   Virtus::Attribute::String.accepted_options
-    #   # => [:primitive, :complex, :accessor, :reader, :writer]
+    #   # => [:primitive, :accessor, :reader, :writer]
     #
     # @return [Array]
     #   the array of valid option names
@@ -241,7 +241,7 @@ def self.primitive?(value)
 
     DEFAULT_ACCESSOR = :public
 
-    OPTIONS = [ :primitive, :complex, :accessor, :reader, :writer, :typecast_method ].freeze
+    OPTIONS = [ :primitive, :accessor, :reader, :writer, :typecast_method ].freeze
 
     accept_options *OPTIONS
 
@@ -262,24 +262,10 @@ def initialize(name, options = {})
 
       @instance_variable_name = "@#{@name}".freeze
       @typecast_method        = @options.fetch(:typecast_method)
-      @complex                = @options.fetch(:complex, false)
 
       set_visibility
     end
 
-    # Returns if an attribute is a complex one
-    #
-    # @example
-    #   Virtus::Attribute::String.complex?  # => false
-    #   Virtus::Attribute::Array.complex?   # => true
-    #
-    # @return [Boolean]
-    #
-    # @api public
-    def complex?
-      @complex
-    end
-
     # Returns value of an attribute for the given instance
     #
     # @example

lib/virtus/attribute/array.rb

@@ -15,7 +15,7 @@ class Attribute
     class Array < Object
       primitive       ::Array
       typecast_method :to_array
-      complex         true
+
     end # class Array
   end # class Attribute
 end # module Virtus

lib/virtus/attribute/hash.rb

@@ -15,7 +15,6 @@ class Attribute
     class Hash < Object
       primitive       ::Hash
       typecast_method :to_hash
-      complex         true
 
     end # class Hash
   end # class Attribute

spec/unit/shared/attribute.rb

@@ -5,5 +5,4 @@
   it_behaves_like 'Attribute.primitive?'
   it_behaves_like 'Attribute#set'
   it_behaves_like 'Attribute#get'
-  it_behaves_like 'Attribute#complex?'
 end