[+TASK] FLOW3 (Reflection): Added a new helper method in ObjectAccess which can traverse object graphs (with the "."-Syntax)
[+TASK] Fluid (ViewHelpers): Refactored the generation of the hidden identity field.
[+FEATURE] Fluid (ViewHelpers): properties of nested objects are now correctly outputted, and the identity fields for the nested objects are generated as well. Related to #4218.