[FEATURE] Implement clearCacheCommand to remove cached pageTSconfig file
[TASK] Refactor loading of page TS config into ConfigurationService

This allows us to execute the reading of TS configuration which defines fields, at a much more opportune time in relation to the TYPO3 environment (DB etc). The result is a much more stable processing of configuration.
[TASK] Remove the now unused "Core" class
[TASK] Whitespace correction, ConfigurationService
[TASK] Refactoring ConfigurationService: buildWizardTabItem method
[TASK] Refactoring ConfigurationService: variable assignment sanitation
[TASK] Refactoring ConfigurationService: buildAllWizardTabsPageTsConfig method
[TASK] Refactoring ConfigurationService: buildAllWizardTabGroups method
[TASK] Refactoring ConfigurationService: getContentObjectConfigurationFromTemplateFile method
[TASK] Refactoring ConfigurationService: remove unused variable
[FEATURE] Use Flux's FlexForm Service to get FCE object configurations

This allows two new features/behaviours/supports:

* Fluid ViewHelpers can be used in argument values on flux:flexform
* The flux:flexform tag can be broken up into multiple lines

A major improvement, support-wise, over the previous behaviour which was to preg_match the template source.
[TASK] Tiny performance improvement by earlier return, ConfigurationService
[TASK] Improve names of pageTsConfig FCE definitions

…by using an underscore to replace invalid chars rather than removing those chars.
[TER] 2.2.0