Fixes #8416

Fixes #8629

Fixes #8800

* Initial HierarchicalDataProvider for TreeGrid
* Initial in-memory hierarchical data implementation
* TreeGrid declarative support

Fixes #8611, Fixes #8620

Closes #8250

* Fixes #8810, #8658

Fixes #8467

* Update frozen column count when a frozen column is removed

Fixes #8658

Emphasise that both location and filename for the design file can be specified in the value parameter.

* RichTextField unnecessarily overwrites clear method

Fixes #8801

Fixes #8734

* Correctly detach components in merged cells

This was already once fixed in 7.7 in #8142

Fixes #8622 
Fixes #8623

Fixes #8722

Fixes #8751

Synchronises parts of compatibility package code to match 7.7
Picks suitable patches for 8 code as well

Fixes #8704

To ensure the resource is automatically closed

* Add Column.getValueProvider to Grid

Fixes #8680

Fixes #8715

* Add @author and @since tags to drag and drop related new files (#8693)

* Allow powerful Navigator subclassing

`protected` methods in `Navigator` permit to create new `Navigator`s to add new capabilities to Vaadin, but `Navigator` fields are still `private` and this limit, for example, the overriding of `Navigator.init`. This PR makes `private` the `Navigator` fields.

* Add documentation blocks to protected fields

Partial fix for #8640

* Fix NPE sorting columns with null values

Sorting a column in Grid throws a NullPointerException if there are null values and we are using the default TextRenderer

* Test for #8610

* Update Grid.java

* Update GridNullValueSortTest.java

* Update GridNullValueSortTest.java

* Add initial implementation of TreeGrid

* Refactor TreeGrid and related classes

* Fix potential class cast exception in TreeGrid#getDataProvider

* Add smoke tests for TreeGrid

* Add communication constants for TreeGrid

Use shared constant values for hierarchy data serialization and deserialization

* Fix event ordering in TreeGrid, add javadocs, keyboard navigation test

* TreeGrid improvements

* Add TreeGrid.getDataProvider to StateGetDoesNotMarkDirtyTest exclude list

* Merge remote-tracking branch 'github/master' into tree-grid

* Remove getEscalator override from TreeGrid

* Make DragSource extension/component available in DropEvent (resolves #8439)

* Update drag and drop test to use new API

* Change type of drag source and update javadoc

* Use existing data map instead of DataTransfer

* Fix java packaging order (#106)

Closes vaadin/archetypes#113

* Use proper UTF-8 encoding for Content-Disposition filenames (#19527) (#6607)

* Enable changing the backing bean for BeanItem (#4302) (#77)

When storing a bean to the database, you typically get a new and updated
bean instance back. By allowing to change the bean instance, we make it
possible to just update the single BeanItem instance which can be used
in many places.

* Make AtmospherePushConnection methods public (#7973)

There is no sensible way to use a custom version of APC, so protected
access does not help in any way to access the underlying resource and/or
connected UI.

* Use correct indexes in multiselect checkboxes after removing rows (#8072)

Fixes #8011

* Fix removal of hidden Grid columns (#8071)

Fixes #8018

* Call error handler for exceptions in UI.init() (#8055)

Fixes #4995

* Render font icon correctly on the 'more' menu item (#8126)

* Render font icon correctly on the 'more' menu item

Fixes #8125

* Reopen Grid details on attach, fixes #8015 (#8074)

Fixes #8015

* Fix broken Grid tests after picking changes from 7.7.7

Removed duplicate setDetailsVisible calls from onDetach

* Correctly detach components in merged cells when a static row is removed (#8142)

Fixes #8140

* Load declarative classes using thread context class loader

Fixes #8528

* Add javadoc warning and example for criteria scripts (#8521)

Fixes #2523

* Fix null caption for NativeSelect and ComboBox

Unified the null caption converting to empty string,
as it was with other selects supporting item caption generator.

Fixes #8630

* Make DragSourceExtension and DropTargetExtension generic (#8440)

* Apply generalization of drag and drop extensions in #8440

* Override javadocs to be more specific

Fix since tags for the server and shared modules and new types in client.

* Add javadoc clarification for DataProivder.refreshItem

* Reduce ComboBox initial requests

Use initial fetched data on client side,
do not request data from server side for each time popup is opened.
Fixed initial filter being null for ComboBox on DataProvider,
causing unnecessary size & fetch for not-changed filter.
Fixed ComboBox sending default filter unnecessarily to server.
Fixed wrong page indexing in VComboBox -> ComboBoxConnector.

Fixes #8496
Fixes vaadin/framework8-issues#488

* Fix last item missing

When pageLength was 0 and nullSelectionAllowed,
the last item was not shown. Tried to sensify the API
for total suggestions versus total suggestions + null selection item.

* Fix ComboBox selected item updates

Handles changing of ItemCaptionGenerator or ItemIconGenerator,
need to update the selected item caption and icon separately.
Previously it worked because all data was sent all the time to client.
Doesn't fix the issue, when selected item is updated with refreshItem(),
and it is not on the active range that will be sent to client.
For that, ComboBox would need a separate notification about item update.

* Updated screenshots

* Add DragSource Extension (#8169)

* Add DropTarget Extension (#8170)

* Add DragStart Event to DragSource Extension (#8171)

* Make DataTransfer.dropEffect configurable (#8174)

* Make DragSource.dataTransfer data configurable (#8172)

* Add server-side Event for drop (#8177)

* Added license headers

* Extract handler methods, move DropEvent and DropListener to new file, move enums to top

* Replaced LinkedHashMap with Map and added List to preserve order of data

* Add API for adding a JS acceptance criteria for dragover and drop (#8178, #8179)

* Make DragSource Extension extendable (#8175)

* Make DropTarget Extension extendable (#8176)

* Added javadoc to protected methods

* Moved EffectAllowed to shared so that it could be used in shared state directly

* Moved DropEffect to separate file, some review fixes and javadoc

* Added list to DropTargetRpc to preserve order of data

* Remove event listeners on unregister

* Changed method names set/getData() to more descriptive set/getTransferData()

* Add server side dragStart event (#8171)

* Add style to prevent text selection to allow drag

* Remove target indicator style on drop

* Add client side dragend event listener for drag source

* Add server side dragend listener.
Attach client side listener only when server side listener added.

* Add drag source information to server side dragstart and dragend events.

* Fixed some issues addressed in review

* Trigger server side dragstart only when there is a listener attached

* Criteria script can be set as null to clear

* Use Js Interop instead of JSNI for handling event listeners

* Use elemental package instead of Js Interop for handling event listeners

* Add missing javadoc for public methods

* Add default value "uninitialized" to effectAllowed parameter

* Simple test UI for HTML5 DnD functionality (#8395)

* Add javadoc and other minor changes