EPUB Output: Do not strip <object> tags with type application/svg+xml

EPUB Output: Do not strip <object> tags with type application/svg+xml in
addition to those that use image/svg+xml. Fixes #1236845 [Conversion - Missing Images](https://bugs.launchpad.net/calibre/+bug/1236845)
Update New York Review of Books

Fixes #1235790 [Private bug](https://bugs.launchpad.net/calibre/+bug/1235790)