[next][properties] Basic properties functionalities....
[next][property] improve thread safety + handle errors
[next][widget] implement basic widget. Removing all event listeners is required at destruction....
[next][event] Refactor event library for handling an optional event source handler and dispatching next to the call. Widget library should use this feature to decorate event calling with source and target properties...
[next][widget] improve widget event binding...
Fix compilation on msvc...