Log Message:
grantlee-qt5: update to 5.2.0

* Increase CMake requirement to version 3.5
* Port scriptable extensions to QJSEngine provided by QtQml
* Support reading properties from Q_GADGETS
* Remove TestCocoon integration
* Clean up documentation to clarify introspection requirements
* Fix mixing of {% include %} and {% extends %} tags
* Fix various bugs discovered by fuzzing
* Remove use of TR1 library features from unit tests
* Remove obsolete build options
* Document that loading templates from Qt Resources is possible