Draft: Port away from QScript

This MR is supposed to finalize the different porting efforts away from script engine.

In this draft the property API for the script objects are switched from properties to functions. Another approach could be to use QJSValue::setProperty instead. Yet in the WIP version a port to used for now to ensure that all unit tests pass, possibly that will be rebased in a later reversion.

Task:

• remove dependency to QScript
• port away from obsolete debugger and remove UI integration
• adapt property system to more restricted behavior of QJSEngine
  • initial port by decoupling node/edge properties from QObject system
  • evaluate port to QJSValue::property system
• update inline API documentation
• port examples
  • introduce autotests for examples
• update UI integration of edge properties
• update UI integration for node properties