Resolves #529. Resolves #404. Added natural sorting filter and tests.

lib/liquid/standardfilters.rb

@@ -122,6 +122,27 @@ module Liquid
       end
     end
 
+    # Sort elements of an array ignoring case if strings
+    # provide optional property with which to sort an array of hashes or drops
+    def sort_natural(input, property = nil)
+      ary = InputIterator.new(input)
+
+      # Quick function that returns the downcased object if it has a downcase,
+      # otherwise it returns the object itself.
+      insensitive = lambda do |obj|
+        obj = obj.downcase if obj.respond_to? :downcase
+        obj
+      end
+
+      if property.nil?
+        ary.sort {|a,b| insensitive.call(a) <=> insensitive.call(b) }
+      elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
+        ary.sort {|a,b| insensitive.call(a[property]) <=> insensitive.call(b[property]) }
+      elsif ary.first.respond_to?(property)
+        ary.sort {|a,b| insensitive.call(a.send(property)) <=> insensitive.call(b.send(property)) }
+      end
+    end
+
     # Remove duplicate elements from an array
     # provide optional property with which to determine uniqueness
     def uniq(input, property = nil)