Reflectionzeug refinements

* Restore default behavior for property guis
* Remove flags in favor of a shared usage of options
* Add convenience accessors for property options
* Fix include style
* Remove obsolete member variables and corresponding functions from Enum- and StringProperty
* Add toVariant to PropertyGroup
I'm not convinced by this change. The name is not an option, it's mandatory for all properties. Furthermore you can easily bypass the regex check in `setName()` by setting the name through `setOption()`. The intention behind the options map was to support later extension and not to replace well-known features with it.