[BUGFIX] Fixed implementation of preProcess() hook in 6.0

This update fixes the following issue:
https://github.com/NamelessCoder/flux/issues/19

See code comment in ext_localconf.php for more.
Merge pull request #21 from murderfacemurderfacemurderface/Issue_19

[BUGFIX] Fixed implementation of preProcess() hook in 6.0
[FEATURE] Add ViewHelper to convert raw FlexForm XML into an array
[TASK] Make uid argument optional
[TASK] Make arguments required, fix docblock
[TASK] Add simple validation for arguments
Merge pull request #22 from dreipunktnull/viewhelper/flexform/data

[FEATURE] Add ViewHelper to convert raw FlexForm XML into an array
[TER] 5.1.1
[TASK] Add support for getting field's value from current template variables
[FEATURE] Add getFlexFormValues and getInheritanceTree methods to ConfigurationProviderInterface
[FEATURE] Flux variable sliding based on parentFieldName

This first phase allows simple, unconditional inheritance with merging of variables based on the inheritance tree. Also added is processing which strips off values which are unchanged in the local element, saving only the diff of inherited+local settings.

This means that in order to be fully restored, variables must also be retrieved by the ConfigurationProvider which then takes care of re-parsing the inheritance tree, merging variables to construct the proper full set of relevant variables.
[TASK] Implement level 2 cache for ConfigurationService
[TASK] Cache TypoScript sub configuration
[BUGFIX] When running nheritance, use actual table name and parent field name
[TASK] Drop ValidatorService

Every possible error this Service could detect and warn about in a friendly manner, the debug mode can now handle. This overall increases performance and reduces code.
[TASK] Got rid of convertDataStructureToFlexFormContent method

No longer needed - and was only a short wrapper function.
[TASK] Implement level 2 cache for inheritance trees
[TASK] Implement level 2 cache for merged configurations
[TASK] CGL cleanups to 100% according to metrics.typo3.org