3.5.2

Tweaks:

• Issue #472: add parents to term export.
• Fail import terms if too many or few fields in data.
• Disable CSRF check for form posts.

Fixes:

• #454: ignore duplicate tag added to Term.
• Show underline for links in error screen, was confusing.
• Allow offline images upload, don't throw 500 error.
• Revert PR #459 (cblanken/issue-379-dictionary-tab-autofocus).