Add optional resource usage limitations to number of rendering calls, length of rendering output and/or number of variable/capture assignments

lib/liquid/errors.rb

@@ -1,6 +1,6 @@
 module Liquid
   class Error < ::StandardError; end
-  
+
   class ArgumentError < Error; end
   class ContextError < Error; end
   class FilterNotFound < Error; end
@@ -8,4 +8,5 @@ module Liquid
   class StandardError < Error; end
   class SyntaxError < Error; end
   class StackLevelError < Error; end
+  class MemoryError < Error; end
 end