+fixed parsing issue with length(...) / adaptation to newer bnf related to #70

	//TODO: try to remove extra=ExtraMatchingAttributes? from this rule 

Assignment:

	ref=VariableRef ASSIGNMENTCHAR (expression=Expression | body=TemplateBody) extra=ExtraMatchingAttributes?;

	ref=VariableRef ASSIGNMENTCHAR (body=TemplateBody | expression=Expression) extra=ExtraMatchingAttributes?;

VariableRef:

	ref=ReferencedValue /*ext+=ExtendedFieldReference*/;