Revert 245816ab27 (fixes #348)

Make keyword mutes operate on plain text input

Nokogiri linked to the version of libxml2 shipped in Travis' Trusty
image exhibits incorrect behavior when parsing strings resembling

    <p>I <3 oats</p>

In particular, Html2Text.convert (which uses nokogiri) will return "I"
for the above string when it ought to return "I <3 oats".

The version of libxml2 shipped with nokogiri 1.8.1+ exhibits correct
parse behavior for this string, as does the libxml2 present in Ubuntu
Xenial.

Since 245816ab2721f386184878d71be01143d207abf5, IntersectionObserverArticle
assumes that its children do not change unless the number of children changes.

This is not the case with the notification overlay, which resulted in the
checkmark of notification cleaning mode not updating unless scrolling to make
notifications appear/disappear.

This change may negatively impact performances.

This allows us to match URLs inside link hrefs.

Unlike strip_tags, html2text will preserve text present in other nodes,
e.g. anchor tags:

    [1] pry(main)> str = '<a href="http://www.example.com">A link</a>'
    => "<a href=\"http://www.example.com\">A link</a>"
    [2] pry(main)> Html2Text.convert(str)
    => "[A link](http://www.example.com)"
    [3] pry(main)> include ActionView::Helpers::SanitizeHelper
    => Object
    [4] pry(main)> strip_tags(str)
    => "A link"

Preserving the href of an anchor allows keyword mutes to also match on
URLs, which is something that the frontend regex filter can currently
do.

The class helps out with keyword mutes, not just some general concept of
"filtering".

Also add HTML entity decoding to Glitch::FilterHelper, which is needed
to e.g. match "<" to the tag-stripped version of "<p><3</p>" or
"<p>&lt;3</p>".

Conflicts:
	.travis.yml
	app/lib/user_settings_decorator.rb
	app/models/user.rb
	app/serializers/initial_state_serializer.rb
	app/views/stream_entries/_detailed_status.html.haml
	app/views/stream_entries/_simple_status.html.haml
	config/locales/simple_form.en.yml

* Added #link_header spec

* Added #perform_request spec

the slight mismatch in hashtag regex between js and ruby was causing
hashtag warning to be displayed for unlisted tweets when an invalid
hashtag was entered

exact version of ruby regex not possible in js as POSIX bracket
expressions are not supported, this version approximates and doesn't
give same unicode support

Conflicts:
	.env.production.sample
	app/controllers/auth/confirmations_controller.rb
	db/schema.rb

* upgrade vagrant box to xenial

this allows the redis version to be upgraded to support the new redis
features used in the activity tracker

* add libpam0g package to vagrant box

this is required for native extensions of gems to build after the
addition of PAM support was added in #5303

* Add option to show only local toots in timeline preview
Right know, toots from all the known fediverse are shown in the main
page of an instance. That however doesn't reflect the instance itself.
With this option the admin may choose to display only local toots so
that users checking the instance get a better idea of internal
conversations.

* Fix issues pointed by codeclimate and eslint

* Add default message for community timeline

* Update pl.yml

* Cas authentication feature

* Config

* Remove class_eval + Omniauth initializer

* Codeclimate review

* Codeclimate review 2

* Codeclimate review 3

* Remove uid/email reconciliation

* SAML authentication

* Clean up code

* Improve login form

* Fix code style issues

* Add locales

Fix detailed-status

The database and Redis do not need external connections, so isolate them
and prevent unauthorized access.

It is required for ApplicationController.

Conflicts:
      app/javascript/styles/mastodon/components.scss

* moved save button

* added save back to the bottom

* Update show.html.haml

They were redundant, and also had a inconsistency; the button for
"other instances" had an icon for the external link in "more" page, but
it didn't in the other pages.

This unifies the implementation, and the external link icon is now shown
in all the about pages.

* add pam support, without extra column

* bugfixes for pam login

* document options

* fix code style

* fix codestyle

* fix tests

* don't call remember_me without password

* fix codestyle

* improve checks for pam usage (should fix tests)

* fix remember_me part 1

* add remember_token column because :rememberable requires either a password or this column.

* migrate db for remember_token

* move pam_authentication to the right place, fix logic bug in edit.html.haml

* fix tests

* fix pam authentication, improve username lookup, add comment

* valid? is sometimes not honored, return nil instead trying to authenticate with pam

* update devise_pam_authenticatable2 and adjust code. Fixes sideeffects observed in tests

* update devise_pam_authenticatable gem, fixes for codeconventions, fix finding user

* codeconvention fixes

* code convention fixes

* fix idention

* update dependency, explicit conflict check

* fix disabled password updates if in pam mode

* fix check password if password is present, fix templates

* block registration if account is maintained by pam

* Revert "block registration if account is maintained by pam"

This reverts commit 8e7a083d65.

* fix identation error introduced by rebase

* block usernames maintained by pam

* document pam settings better

* fix code style