* Add Minz_View::_path method (replace change_view)
The `_path` method is more powerful since it allows to choose the file
extension. It is also Minz_Request-agnostic, which is useful to reuse
the Minz_View class in other places.
`change_view` is now deprecated and a warning is logged if we use it.
* Provide a Minz_Mailer to send emails
It uses PHPMailer under the hood and only supports PHP >= 5.5
* New extension event + Tumblr GDPR
https://github.com/FreshRSS/FreshRSS/issues/1894
simplepie_before_init event
* Refactor extension enabling + Tumblr GDPR enabled by default
Add possibility for extensions to be enabled by default, and disabled
back by users.
* Minor whitespace
