Merge pull request #210 from kojix2/execution_count_reply_error

Add execution_count on reply error messages.

Author: kojix2

lib/iruby/kernel.rb

@@ -94,6 +94,7 @@ def execute_request(msg)
         content = error_content(e)
         @session.send(:publish, :error, content)
         content[:status] = :error
+        content[:execution_count] = @execution_count
       end
       @session.send(:reply, :execute_reply, content)
       @session.send(:publish, :execute_result,