Merged last set of changes from original SVN location

lib/liquid/errors.rb

@@ -1,7 +1,10 @@
 module Liquid
-  class FilterNotFound < StandardError
-  end
-
-  class FileSystemError < StandardError
-  end
+  class Error < ::StandardError; end
+  
+  class ArgumentError < Error; end
+  class ContextError < Error; end
+  class FilterNotFound < Error; end
+  class FileSystemError < Error; end
+  class StandardError < Error; end
+  class SyntaxError < Error; end
 end