Bundle Latest REXML

Sam Ruby has been doing a bang-up job fixing the bugs in REXML.
Who knows when these improvements will trickle down to vendor distributions of Ruby.
In the meantime, let's bundle the latest version of REXML with Instiki.
We check the version number of the bundled REXML against that of the System REXML, and use whichever is later.

vendor/plugins/rexml/lib/rexml/node.rb

@@ -0,0 +1,75 @@
+require "rexml/parseexception"
+require "rexml/formatters/pretty"
+require "rexml/formatters/default"
+
+module REXML
+	# Represents a node in the tree.  Nodes are never encountered except as
+	# superclasses of other objects.  Nodes have siblings.
+	module Node
+		# @return the next sibling (nil if unset)
+		def next_sibling_node
+			return nil if @parent.nil?
+			@parent[ @parent.index(self) + 1 ]
+		end
+
+		# @return the previous sibling (nil if unset)
+		def previous_sibling_node
+			return nil if @parent.nil?
+			ind = @parent.index(self)
+			return nil if ind == 0
+			@parent[ ind - 1 ]
+		end
+
+    # indent::
+    #   *DEPRECATED* This parameter is now ignored.  See the formatters in the
+    #   REXML::Formatters package for changing the output style.
+		def to_s indent=nil
+      unless indent.nil?
+        Kernel.warn( "#{self.class.name}.to_s(indent) parameter is deprecated" )
+        f = REXML::Formatters::Pretty.new( indent )
+        f.write( self, rv = "" )
+      else
+        f = REXML::Formatters::Default.new
+        f.write( self, rv = "" )
+      end
+      return rv
+		end
+
+		def indent to, ind
+ 			if @parent and @parent.context and not @parent.context[:indentstyle].nil? then
+ 				indentstyle = @parent.context[:indentstyle]
+ 			else
+ 				indentstyle = '  '
+ 			end
+ 			to << indentstyle*ind unless ind<1
+		end
+
+		def parent?
+			false;
+		end
+
+
+		# Visit all subnodes of +self+ recursively
+		def each_recursive(&block) # :yields: node
+			self.elements.each {|node|
+				block.call(node)
+				node.each_recursive(&block)
+			}
+		end
+
+		# Find (and return) first subnode (recursively) for which the block 
+    # evaluates to true. Returns +nil+ if none was found.
+		def find_first_recursive(&block) # :yields: node
+      each_recursive {|node|
+        return node if block.call(node)
+      }
+      return nil
+    end
+
+    # Returns the position that +self+ holds in its parent's array, indexed
+    # from 1.
+    def index_in_parent
+      parent.index(self)+1
+    end
+	end
+end