copying plugins to inherited classes; set a default options also for the main module

lib/httpx/chainable.rb

@@ -60,6 +60,10 @@ module HTTPX
 
     private
 
+    def default_options
+      @default_options || Options.new
+    end
+
     # :nodoc:
     def branch(options)
       Client.new(options)

lib/httpx/client.rb

@@ -79,6 +79,7 @@ module HTTPX
       def inherited(klass)
         super
         klass.instance_variable_set(:@default_options, @default_options.dup)
+        klass.instance_variable_set(:@plugins, @plugins.dup)
       end
 
       def plugin(pl, *args, &block)