Added select(Collection<T>) and deselect(Collection<T>) methods
to selection model multi.

Fixes #8253

Fixes vaadin/framework8-issues#569

* Add DataProvider refreshItem for single item update

* Add 'id' concept for DataProviders

This patch also adds a simplified data provider that can replace items
based on their id. This can be used to simulate stale objects from an actual
backend.

* Add refresh logic to Grid SelectionModels

* Remove broken equals and hashCode

* Refresh KeyMapper, clean up some methods

* Fix UI.access in test

* Fix tests and Grid single selection model

* Do clean up before replacing data provider

* Check correct variable for null value

* Fix other selects, add generic tests

* Code style fixes, removed assert

* Merge remote-tracking branch 'origin/master' into 286_refresh_items

* Fix documentation for refreshing an item

* Improve introduction chapter, minor clarifications

* Merge remote-tracking branch 'origin/master' into 287_refresh_items

* Add missing parameters in unit tests

Note that not all browsers yet support HTML imports. If a polyfill
is needed to load HTML imports, it must be loaded before HTML Imports
can be loaded. There is no automatic loading of any polyfills.

The immediate benefit of this change is that ComboBox doesn't have to do
any wrapping when a ListDataProvider is set. A secondary benefit is that
a bunch of redundant type parameters and unsafe casts can be removed.

This is one of many steps towards #8245

* Use non-Generic SortOrder in Query.

Fixes #8215

* Allow distinct configurable filter and wrapped filter types

This enables implementing the use case that was already described
towards the end of datamodel-providers.asciidoc.

Also swaps the order of the callback type parameters to make all three
match the order of the ConfigurableFilterDataProvider type parameters.

* Serve VAADIN files also from META-INF/resources (#8286)

Fixes #8206

Cannot overload the same create method for this purpose since it
conflicts with T... overload. Each case is instead given its own
descriptive but still discoverable method name.

* Make BeanBinderPropertySet exclude Object properties

* Method names unified to withXyzFilter
* withConfigurableFilter moved to DataProvider
* Remove DataProviderWrapper.convert since it does the same as
DataProvider.withConvertedFilter
* Make javadocs slightly more consistent
* Make type parameters consistent

* Use getFirstSelectedItem() instead of getFirstSelected().

Fixes vaadin/framework8-issues#596

* Fix absolute layout component sizing on size change (#8255, #8256, #8257)

Changing from relative to defined size leaves the component positioned wrong,
also changing from defined size to relative size leaves the component in the
wrong position with the wrong size.

Change makes the wrapper rerun setChildWidgetPosition() that adds/removes
necessary css definitions to/from the cssPosition String.

* Clean test sources according to review.

When using async='false' for scripts created by scripts
the execution order is guaranteed to be the same as the order the
script tags are created

Fixes #5339, #3631

* Fix BeanBinderPropertySet to not deserialize into multiple instances

* Remove outdated filtering concepts

withFilter is removed since filters are supposed to be set as state in
the data provider instead of by wrapping.

AppendabileFilterDataProvider is removed since the data provider is
supposed to do any appending when updating its own state instead of
through wrapping.

This is one of many steps towards #8245

* Migration guide 1st draft

* Restructure and improve migration guide

* Update migrating-to-vaadin8.asciidoc

Also updates ComboBox.setItems to use these new shorthands

This is one of many steps towards #8245

* Add a data provider wrapper with a configurable filter

This is one of many steps towards #8245

* Overload AbstarctComponent.setDescription() with content mode parameter

Fixes #8185

* Introduce DateTimeFile and InlineDateTimeField.

Fixes #8132

* Correct and provide declarative tests.

* Provide a date converter and UI tests.

* Change BackEndDataProvider into an interface

BackEndDataProvider is now an interface with methods for setting
sorting options based on SortOrder instances. 

AbstractBackEndDataProvider stores sorting options, combines them with
the sorting provided in the query and invokes its own abstract fetch and
size methods.

CallbackDataProvider implements a BackEndDataProvider based on two
lambdas.

This is one of many steps towards #8245

* Allow setting filters directly in ListDataProvider

This is one of many steps towards #8245

* Simplified javadoc

* Better instructions in widgetset optimization view in the debug window.

The generated example code is ok, but steps to use them are not obvious.
Added more details to debug window instructions to make it clear what steps are
needed to optimize the widgetset.

Change-Id: Id46632697044223092ef772f98b1fcd69c28d0da

* Make data providers statefull with regards to default sort orders

This is one of many steps towards #8245

* Add getHeaderCellByCaption method to tb-api GridElement

* Add separate modules to test Bean Validation lib necessity.

Fixes #8141

Closes #8232

Without this, maven.compiler.source will not be set to 1.8 which
sometimes seems to make Eclipse think it should use Java 5 compiler
settings for the project, causing various issues.

* Removed obsolete 'Setting up the Development Environment' link in tutorial'

* Added support for HTML5 push/replaceState for proper deep linkin features

* Automated test script now works at least on chrome

* Uses html5 push/popstate to implement uri fragment feature

* fire legacy fragment change events also via popstate events rpc calls
* send new fragments via pushstate mechanism

* formatting

* Formatting and adding test and workaround for IE bug

* Formatting and depracated UriFragmentListener

* Aligned naming in the new API

* Ignored IE due to web driver bug

Tested a workaround with javascript based window.location.href fetch,
but that don’t seem to work stable enough.

* Add "deselect allowed" feature to the Grid.

Fixes #8149

Fixes #7005

* Replace Listing with HasDataProvider and HasFilterableDataProvider

The type parameters of the Listing interface does in practice mean that
it isn't useful for anything. This patch replaces that interface with
separate types for components that require filterable data providers and
components that support any kind of data provider.

The setItem methods are extracted to a common interface that is also
directly implemented by AbstractListing.

* Fix TestBench API imports, move functionality from custom elements

* Fixes to TestBench APIs and JavaDocs

* Merge remote-tracking branch 'origin/master' into 578_tbapi_cleanup

* Fix method name in CheckBoxGroupTest

* Remove unused custom element classes

* Implement getOptions using getOptionElements

* Replace setValue with setSelection in CheckBoxGroupElement

* Rename CheckBoxGroupElement getSelection to getValue

* Fix one last method

* Avoid using Guava API in the documentation

* Include old value in ValueChangeEvent