Added functions to check etag of elements

Fix password strength meter tooltip message

* Update sabre/dav to 3.2.0

* Adjust code to work with sabre/dav 3.2.0 and it's dependencies

* Adding own CalDAV plugin to fix calendar home property

* Test if there is a user logged in when listing files home

* Update sabre version used by integration tests

* Disable unauthenticated DAV access

This is needed to make Sabre 3.2 behave like we did before.
Eventually we should integrate better with the ACL plugin which itself
should implement an auth failure when appropriate.

Upgrade bootstrap tooltip.css from v3.3.5 to v3.3.6

Allow php 5.3 syntax in index.php so that the proper error can be generated and not a parse exception - fixes #26317 (#26330)

* Allow registering of OCS routes with the appframework

* Make the router handle OCS AppFramework Routes

* Make the OCS endpoint handle the new OCS AppFramework routes

* Move Sharees api over to use OCSController

* Move federation api over to use OCSController - fixes #20771

* Inject router into url generator and make tests db independent

* Fixing typo

* Fixing unit tests in federation and sharing related to changes in ocs routes

* Default response format for OCS is xml

* Handle LoginException in ocs calls

* Fix comment

* Fix webroot in router

* Adding undefined field in SessionMiddleware

* Federation handshake calls do no require any authentication

* Adding integration test to ensure that federation handshake behaves properly

Fail earlier on Windows.

App dependencies are now analysed on app enable as well - not only on app install.

There is a setup check that prevents installing on Windows.
No need to keep the old unsupported Windows code paths.

Also fix the posix test that was running the wrong verify method:

The call to UserList.add() was wrong and was passing "user.lastLogin"
as the sort argument which would cause the list to be resorted over and
over again for every added item after loading the next page of users.

Fixes incorrect loading of file when using the console from a sibling OC instance directory (#26301)

The check for two factor enforcement would return true for non-existing
users. This fix makes it return false in order to be able to perform
the regular login which will then fail and return false.

This prevents throwing PasswordLoginForbidden for non-existing users.

* Store avatars outside of the home

Inside a hidden "metadata-avatars" folder.
Doesn't require home FS setup

* Fix it

* Store avatars in e.g. a/d/admin, using md5 on non alphanumeric characters and refactor tests

* Always do an md5 of the user name

* Update Util.php

* Adjust avatar migration version check

* Fix LazyRoot folder to properly return get() value

* Fix avatar migration with the new folder

* Don't fail move avatar step if user has no home at all

* Fix use statement for IRootFolder

* Bring social icons to core

* Introduce social sharing

* Add missing mail-grey.svg

* Add config option to disable social sharing

* Smaller icons

* Twitter: set shared link as url in twitter field

* Fix tooltip to disappear on click

* Show avatar in share drop down

* Fix share autocomplete vertical align with avatar

Move OC\Files\Storage\Shared to the right namespace

Storage 503 message improvements