Class whose purpose is dedicated to resolving classes which
can be used as ViewHelpers and ExpressionNodes in Fluid.
In addition to modifying the behavior or the parser when
legacy mode is requested, this ViewHelperResolver is also
made capable of "mixing" two different ViewHelper namespaces
to effectively create aliases for the Fluid core ViewHelpers
to be loaded in the (TYPO3|Neos) scope as well.