Support array properties in Duktape backend

[j-o]

It should be possible to create a Property<std::vector<int>>("myArray", ...) and access its elements from JS as myObj.myArray[x].

Currently, I see two issues that must be addressed:

• [ ] the typed-library does not recognize std::vector as an array type, only std::array
• [ ] the Duktape backend does not expose arrays as such