Clear contents of iframe clone that is in a Window so that when it's reattached to DOM we don't get 404

Navigation needs to be done also in doRefresh(..) in similar fashion as in doInit(..)

Fixes https://github.com/vaadin/framework/issues/11416

* Add Javadoc to the ScrollTo methods in TreeGrid

* Clear up enhancements contents from master

* Upgrade the version mentioned in the release note

* Close the <span> block

* add possibility to configure nested null behavior to Grid.Column

* added addColumn method that allows configuring the nested null handling behavior of the column

* added uitest for nested null value handling, implements #11137

* Release-note updates

Change the word for describing icon swapping

* Update vaadin slogan in the release-note template

* Some formatting changes

* add client side integration for custom styles for checkbox.label and checkbox.input

* add server side integration for checkbox element styling

* add server side tests

* add client side test

Updated versions to latest ones as people often just copy past things. Added comment to urge people to use the versions they need. Removed version from archetype to use the latest by default.

* Improve VMenuBar click handling logic

During `updateFromUIDL` inside MenuBarConnector we empty and re-instantiate the components of MenuBar. When we are modifying the Menubar from the BlurEventListener of another component, we ,by this, remove widgets, therefore clickEvent is not fired and the action of the MenuItem is not proceed as a result. (The BlurEvent is fired before the click event in the chain of events. )

To improve the situation, we catch onMouseDown event , which is fired before BlurEvent,by assigning mouseDown flag to true. Then if no click event has yet happened, we delay the execution of update inside `updateFromUIDL` by default 500 ms. Then if click event occurs, it proceeds normally. The time can be increased/decreased using setter.

There is no delay, if we are clicking on the MenuBar as usual or no Blur listener is set.

This change allows setting descriptions

* Remove accidentally committed comment

* Don't update the state on the getDelayMs call

There are not [source, java] tags.

* Update clientsideapp-entrypoint.asciidoc

Adding missing ```[source, java]```

Some snippets codes do not render properly.

* Update README-TESTS

Add formatting for easy-reading;
Add missing configuration for running IE11 locally.

* Fixes #10814

* Add missing tests

Fixes #11374

Update screenshots due to update of search-minus and search-plus icons values

* Move onClick logic to the Connector

Move onClick event handling from 'VNativeButton' to NativeButtonConnector. Now works as for regular button.

Also, adding propagation of the `enabled` value to the state on disableOnClick being true

Fixes https://github.com/vaadin/framework/issues/11188

Setting read-only state to CheckBoxGroup should disable adding clicking effect. Missing v-readonly style is added to every CheckBox in the component, if it's set to read-only.

Fixes: https://github.com/vaadin/framework/issues/11113

* Add file missed from initial commit

* Verifying that option is enabled

Some of the options might be disabled on there own. Verify that option is not disabled, before removing disabled styles.

* Add missing test file

* Complete the empty since tag

The instructions for applying the license in Designer are wrong and outdated. Remove them.

* Request data update before client response

* fix the accidental commit

* add tests

fixes #11320

* Add missing FocusShortcutListener

Was removed from 8.0 and not readded.

Fixes #8297

* Update Release note for this change

7.1. (#11156)
* This the range might be necessary to increase when Liferay 7.2 or
newer has been released.

In certain cases setting the frozen columns didn't produce the expected result in the client side widget state. This happened if the frozen columns value was set to be the same it was before removeAllColumns was called.

This fix removes the frozen column value from the diff state so that the value gets properly set in the client side.

Closes #10653

* Add more context information to criteriaScript in GridDropTargetConnector

When using drag and drop in Grids and TreeGrids a criteriaScript can be specified.
However, this criteriaScript only gets an event as input parameter.
It would be helpful if the criteriaScript would get more information:
- the DropLocation
- the targetElement which is used as a base for the DropLocation

This change provides a protected method in DropTargetExtensionConnector
which decides, if the drop is allowed by the criteriaScript.
This method is overriden in GridDropTargetConnector to
provide the both parameters dropLocation and targetElement.

* add Test UI for criteriaScript with targetElement and dropLocation

* add some description for the Test UI

* Improvements to updating spacer indexes.

- When details rows are moved down, indexes need to be updated from
bottom up.

Fixes #11352

- When rows are added, details row heights need to be taken into account
in positioning.

Fixes #11348

* Descriptive comment for TwinColSelect - no lazy load #11025

It documents the issue #11025

https://github.com/vaadin/framework/issues/11025#issuecomment-443506307

* Fixing dynamic resource registration after activation

* Fixed formatting

* Fixed formatting

* Merge branch 'master' into osgi-dynamic-fix