[BUGFIX] Fix wrong test in method registerProviderExtensionKey

According to the method definition $extensionKey is given as string.
Assuming, the logic is to search an extension key from an array of
extensions, the test must be fixed solving a warning on the FE.
Merge pull request #136 from fudriot/patch1

[BUGFIX] Fix wrong test in method registerProviderExtensionKey
[TASK] Remove unused code
Merge pull request #137 from dreipunktnull/master

[TASK] Code cleaning
Merge pull request #135 from fudriot/master

[BUGFIX] Fix Warning if configuration wizard is empty
[BUGFIX] Add required uid field to select statement
Merge pull request #138 from dreipunktnull/master

[BUGFIX] Fix inheritance in DataViewHelper
[BUGFIX] Always add "clear value" wizard
Merge pull request #139 from dreipunktnull/master

[BUGFIX] Always add "clear value" wizard
[BUGFIX] Inserting element after another in content area sorts wrong

Fixes: https://github.com/FluidTYPO3/fluidcontent/issues/55
Merge pull request #140 from NamelessCoder/sortingafter

[BUGFIX] Inserting element after another in content area sorts wrong
[FEATURE] "Is reference" indicator and link to anchored original

Allows straight-to-position jump to original element if current shortcut-type element is a reference to a single content element - which is how Flux stores references.

Fixes: #41
Merge pull request #141 from NamelessCoder/reference

[FEATURE] "Is reference" indicator and link to anchored original
[TASK] Expose getName on fields to read post-facto
[FEATURE] FlexForm field palettes

Used as a container element around fields, this ViewHelper intercepts child fields and adds them to a palette (in FlexForm terms, this is merely a DHTML-collapsible section which causes nesting of variable names).
[BUGFIX] Missing visual filename in group field if value is inherited

Not a neat fix, but a fix nonetheless.

Fixes: #134
[BUGFIX] Using Flux with other v4-only hook subscribers

This fixes an issue with expected class names in hook subscribers which either don't want to or can't remove a forced type indication for the "caller" parameter.

Before, Flux extended the new class names and since the new class names don't extend the old ones (it's vice versa), hook subscribers which have a hard expectation of an old class, would fail because of receiving a new class.

After, Flux now subclasses the old class which subclasses the new class that Flux used to subclass - result is same behaviour as now, one additional level in the inheritance tree and compatibility with v4-only hook subscribers.

Fixes: #125
[BUGFIX] Use Web-scope Request and Response for 4.5 compatibility

Described in and fixes: #142
Merge pull request #149 from NamelessCoder/missinglabel

[BUGFIX] Missing visual filename in group field if value is inherited
Merge pull request #150 from NamelessCoder/ancestorsarebetter

[BUGFIX] Using Flux with other v4-only hook subscribers