• Return null from WebLoader on missing template instead of throwing an
  error, for consistency with other loaders. This allows WebLoader to support
  the new ignore missing flag on the include tag. If ignore missing is
  not set, a generic "template not found" error will still be thrown, just like
  for any other loader. Ajax errors other than 404 will still cause WebLoader
  to throw an error directly.
• Add preserve-linebreaks option to striptags filter. Thanks Ivan
  Kleshnin. Merge of #619.