Fix Nokogiri parser processing xml entity encoded characters

lib/nori/parser/nokogiri.rb

@@ -19,15 +19,27 @@ def start_element(name, attrs = [])
           stack.push Nori::XMLUtilityNode.new(options, name, Hash[*attrs.flatten])
         end
 
+        # To keep backward behaviour compatibility
+        # delete last child if it is a space-only text node
         def end_element(name)
           if stack.size > 1
             last = stack.pop
+            maybe_string = last.children.last
+            if maybe_string.is_a?(String) and maybe_string.strip.empty?
+              last.children.pop
+            end
             stack.last.add_node last
           end
         end
 
+        # If this node is a successive character then add it as is.
+        # First child being a space-only text node will not be added
+        # because there is no previous characters.
         def characters(string)
-          stack.last.add_node(string) unless string.strip.length == 0 || stack.empty?
+          last = stack.last
+          if last and last.children.last.is_a?(String) or string.strip.size > 0
+            last.add_node(string)
+          end
         end
 
         alias cdata_block characters