With this patch, in addition to document nodes, you can also have
content nodes (partials) re-rendered via AJAX requests. The identifier
of the node is now stored in the cache entry along with the Fusion
path and is thus available on request to render the partial.

A key feature of this package is to associate a partial with a unique
partial key for later dedicated rendering in AJAX requests. The
implementation strictly relied on a defined position of the responsible
Psmb.Ajaxify:RenderPath within the Psmb.Ajaxify:Ajaxify Fusion
object. With this patch, that relationship has been relaxed: the
Psmb.Ajaxify:RenderPath Fusion object can now be used both standalone
and nested within any depth of Psmb.Ajaxify:Ajaxify. However, when
used standalone, it must be called at the first level of the partial -
in the same way as Psmb.Ajaxify:Ajaxify.

Psmb.Ajaxify:Ajaxify and Psmb.Ajaxify:RenderPath can be assigned to
the same generic property name in all occurrences for better code
readability.

The partial key must be unique per Fusion path and content node.
Therefore, the current state of one key per Fusion path is not
sufficient. With this patch, the key will be a hash based on both
attributes.

The hash is generated automatically, thereby removing the requirement
for the developer to manually specify a unique key.

Because this patch changes the value of the publicly used URL parameter
`&ajaxPathKey=<value>` this patch is marked as breaking.

Previously, partial rendering considered only the Fusion path. With the
recent changes, both the Fusion path and the content node, called the
partial context, are now considered. Consider this change in the naming
conventions. In detail these are:

- Public: Rename URL parameter "ajaxPathKey" to "ajaxPartialKey".
- Public: Rename `Psmb.Ajaxify:RenderPath` to `Psmb.Ajaxify:PartialSerializer`.
- Public: Rename `Psmb.Ajaxify:RenderPathResolver` to `Psmb.Ajaxify:PartialResolver`.
- Public: Rename "[P]athsCache" to "[Pp]artialCache" cache identifier.
- Private: Use FQDN for \Exception to satisfy the editor :).
- Private: Use verbose common "fusionPath" over "path" and "renderPath".
- Private: Rename "pathKey" to "partialKey".
- Private: Even smaller adjustments ..

Since this patch changes the naming of some public elements, it is marked
as breaking. And breaking changes are included because there were other
breaking changes in this patch already.

Apply PSR-2 and general Neos .editorconfig styles to the codebase to
eliminate mixing of styles and facilitate future patching.