Issue #11246, slightly modified cherry-pick from #11247

* Updated migration related documentation

More detailed information on compatibility components.
Mention vaadin:upgrade8 target in migration guide.

Fixes #8581

This patch updates server side add*Listener methods to return
a registration object and deprecates their corresponding
remove*Listener methods.

Additionally this patch removes add/removeListener methods which were
deprecated in 7.0.

Change-Id: I26ac5f11882512288fbbf601c7cb2aaff653ec76

Change-Id: Icbe1c6a5c0e2b10255424801cada8c11a71decb7

Change-Id: Iba0a35d5ea9a97b0020f506f610630471c59748b

Change-Id: Iacf3864f6902e810591e2085adb44d0a6848f51c

Change-Id: Icdb0ddc011e8749f4c3f159d2ecd94e4c564d28f

* Use com.vaadin.v7
* Use the same class name as in Vaadin 7
* Use a "vaadin7-" declarative prefix for Vaadin 7 components

Change-Id: I19a27f3835b18980b91a4f8f9464b2adde1a5fd5

Because of dependencies also moves
Calendar, ColorPicker, SQLContainer, container filters

Change-Id: I0594cb24f20486ebbca4be578827fea7cdf92108

Change-Id: I6485dee1ebba12b180a9063ed4b530f7dc63cd77

Change-Id: I74c8bda4bf53340a6deb1fcd5bd8db87b502c856

Change-Id: Ic3b427502905dd635a1d26b5a82aaa24228a60bd

Change-Id: Ifdadc24ff922761eb78c4e5168f0e83fbf47108a

This was already in the shared state.

Change-Id: I42f43be136199e6cad259742ee8d7e78c65cf94f

This is an intermediate step towards a different approach
to sending items from server to client.

An unused null selection item attribute was removed, as the
information is currently communicated outside the item.

Change-Id: I7b2cd34d2d05287f91d6859fca28337dccdbe8df

All client to server communication of ComboBox is now done
with RPC.

There is still an empty changeVariables() methods to
override the default behavior in AbstractSelect.

Change-Id: I718eeabd5c116ec4e00485ed37a0a6d5389ee1f0

Change-Id: I7eaf2dae59133745d6a7c686503625f1f5216c52

Use shared state for the page length and update related tests.
This change also removes an unused widget field.

Change-Id: I22055ea058029f898af952252a0c3dadcd9476d4

Send the selection from the client to the server with RPC.

Change-Id: I67e4e526f59550e83d9400729adf91e2b4bbb806

Send focus and blur events using RPC instead of in UIDL.
This change does not use ConnectorFocusAndBlurHandler to preserve
old timings.

Change-Id: I02a86dcc3959388ca835798a33cb600898b19ab9

When the user creates a new item, send it with client to
server RPC.

Change-Id: Iaf60fc910d4e8b57b681b4cf13f124871c1a01b0

Create an empty client to server RPC implementation for ComboBox.

Change-Id: I1ccce4875682b8ba2541acdc42d361edb30ca458

This change uses shared state for the read-only flag, text
input allowed flag and input prompt.

Change-Id: If770a3d9be96d10c3a19654b398bc2f5ddfb7e67

Added API setPopupWidth(String) to ComboBox. The suggestion pop-up now
has three different width modes:

1. Legacy "null"-mode: width is determined by the longest item
caption for each page. This looks & feels like the old implementation.
This is the default mode

2. Relative to the ComboBox. e.g. 100%

3. fixed width using any CSS definition
Change-Id: Id60a6996ee82726196b84d50c2d0d18a6cfb5ebf

Change-Id: I5c740f4e9cb28103bab199f9a552153d82277e7e

Change-Id: I9fe4a332bb8170a6482610d1b83bad73e049a3a1

Change-Id: I376cd27d5ae08c877cd3279740b601fb8dddb2e7

Change-Id: I899c21e3f71bc728cb613685134b99961b557c5b

If scrollToSelectedItem is set to false (which is needed to work
properly with
large datasets) the selected item caption is sent to client with a
special
attribute to avoid the field looking like unselected.

Change-Id: Ib80355c3b52faaaeaa9ab7195644701cc3bf0d15

Change-Id: Id462c3e76c8d761c04851227c949a3124ddf14b3

Change-Id: I663b39a37bcdf4383fa76d04acd127503ced11df

Change-Id: I5b6298be367e4fe820320a5e3fd6bf5aaa7e2047

Change-Id: Ic77338304dc7e58e49f27dcdaf0bab2e00f5bba6

Change-Id: I34525b7d9e78ede7f9533869326ca0c08474963a

Change-Id: I1ac813afa47e38fb508e676d25d103a29bfada6a

Selection is now sent only as a key, removed redundant attribute on the
item.

Change-Id: I882d4ae17a1dc91f7a55a0b4a94e47c078ffc022

ComboBox filtering fix.

Change-Id: Ia274155c15a5319ec0c98d7bc0347e2f2bd0ddbd

Change-Id: I419ce4581d1a8b84d4236a85a1333d23f3423b2e

Change-Id: I92597e49f2dc12c9fb90c2a35a213386da56bb3f

Change-Id: If3fc2c2d9b251cbc6f2a9da2ede23ff17f7362ef

Patch from Pekka with minor changes (ButtonCode -> MouseButton, FilteringMode -> ComboBox)

This permits optimization of data fetches from various containers
where getting single items by index in a loop might be costly.

Also add a helper method in ContainerHelpers to make it easier to
implement the new method where performance of fetching an id by index is
not an issue. SQLContainer still uses this helper instead of an
optimized implementation.

Select now extends ComboBox instead of vice versa
Select is now deprecated in favor of ComboBox