Fixes #10624

Fixes #10284

Fixes #9592

Fixes #7833

Adds the ability to set the content mode for the description of a menu item that is part of a menu bar.
This functionality was already available for every AbstractComponent but missing for the menu items of menu bars.
If no content mode is specified it defaults to the PREFORMATED content mode.

Fixes #10304

* Don't refer to Label
* Explicitly mention XSS risk with HTML

* Rename HierarchicalDataCommunicator#getMapper to getHierarchyMapper

* Make rpc field in Notification private

* Change DropIndexCalculator.ALWAYS_DROP_TO_END to a generic static method

* Move EditorImpl#editRow documentation to the interface level

* Correct GridDragEndEvent, GridDragStartEvent constructor javadocs

* Revert SharedState.registeredEventListeners to a Set

* Rename GridDropTarget dropAllowedOnSortedGridRows

* Rename ColumnState.contentMode to tooltipContentMode

This pathc also switches GridDragger to by default not allow drops on rows when the
grid has been sorted.

* Add new drop mode ON_GRID for GridDropTarget

Also adds a way to not accept drops on rows when the user has sorted the grid.
This way the bad UX can be avoided for showing the drop indicator for the wrong place when the grid has been sorted.
This has not been made default behavior to GridDropTarget since it would change behavior compared to 8.1.
Instead if is triggerable via API in GridDropTarget.

* Refactor sorted grid drop logic to server side

* Block setDropMode calls

Blocking setDropMode set values if the grid has been sorted and drop on
sorted rows is not allowed. The value is used once the grid is not sorted
anymore or the drops are allowed on sorted rows.

* add Grid#Column#get/setAssistiveCaption

* fix test and update doc

* move testGridAssistiveCaption to GridTest

* delete test file

* delete test file

* Delete GridAssistiveCaptionTest.java

* Create GridAssistiveCaptionTest

* Create GridAssistiveCaption

* Rename GridAssistiveCaption to GridAssistiveCaption.java

* Rename GridAssistiveCaptionTest to GridAssistiveCaptionTest.java

* Reformat using eclipse

* Variable names to conform to naming convention.

* Use static constants where it makes sense

* Grid column to be sortable when implemented/supported
* Fix GridDeclarativeTest
* Parameterize to Grid<Person>
* Revert Parameterize to Grid<Person>, JDK with generics.
* Assertions for other columns
* Fix test

Fixes #8792

* AbstractDateField.formatDate to be abstract

Remove invalidDateString paramter, as it can be deduced

* Fix test

* Remove AbstractDateField.getResolutionVariable

VAbstractTextualDate: rename updateDateVariables() to updateBufferedResolutions()

* Revert to use fixed value of MONDAY.

* release notes

* updateAndSendBufferedValues()

* Missed call to updateAndSendBufferedValues();

* release note

* Use .toLowerCase and .toUpperCase(Locale.ROOT)

* Spaces

* add spaces after if(

Opening grid editor from server side.
Fixes #8477.
Addressing #8820 will be the user's responsibility as fetching index of item might be slow.

This changes SharedState.registeredEventListeners to be a Map that keeps track of how many listeners of each type have been added, and handles unregistering of such listeners correctly.

Also removes dependency on junit.framework.TestCase .

Also includes minor other javadoc and formatting fixes.

Converts Notification to an Extension and adds support for listening to the closing of notifications.

Fixes #888

* Navigator now by default uses pushState and normal URLs

* added documentation for pushState and updated Navigator documentation

* improving docs etc, adding one TODO to be solved before merging

* pushState/replaceState no work better with changing titles

* Making uri fragment navigator work when not using specially mapped UI

* Revert to older default, add annotation for selecting

* Fix tests, add null checks

* Reorder if-clause, fix tests

* Revert unnecessary test change

* Use correct variable in UI, fix test clean up

* Updates to JavaDocs, fix some methods and tests

* Add comments, fix test ui, TODO for fallbacks

* Navigation documentation, JavaDocs, removed TODOs

* Documentation fixes

* Improve JavaDocs

* Fix link name in documentation

* Improve throws declaration in getLocation

* Change documentation about the PushState based navigation

* Add since tags

* Add since tags for UI

Add additional class names and style to components and error indicators to distinguish different error levels.

Vaadin 8 implementation of #9816. Cherry picked changes and added compatibility package component changes and tests.

Resolves #3139

And remove unused imports.