[+FEATURE] FLOW3 (Persistence): The persistence framework (Dirty Monitoring Aspect to be exact) now traces if an entity is a clone of an existing (= reconstituted) entity. This allows for intelligently rendering a hidden identity field in forms by Fluid's Form Viewhelper. Relates to #4170
[+BUGFIX] Fluid (ViewHelpers): Added an additional check for rendering the hidden identity field: the hidden field is only rendered for "new" objects if they are in fact a clone of an existing object. Resolves #4170
[~TASK] FLOW3 (Core): Only touched the bootstrap so that all caches are flushed on the next hit, because old proxy classes would call a fatal error otherwise.