Implement instance calls with as statements

[KAYLukas]

To make up for the lack of final methods, we aim to implement a way to call an instance function defined in a specific class (avoiding inheritance). This is a simple variation on instance calls, and should only require some macros. The macro mapping should be along the way of

RBNode* n = ...
RBNode* n = $((n as Node) $ getRoot())
// or...
RBNode* n = $(n as Node $ getRoot())

Maps into

RNode *n = ...
RBNode *n = ({
                        _FoxyC_SyntaxLogic_Runtime_Push_ObjectScope(n);
                        result = Node_CLASS.getRoot();
                        _FoxyC_SyntaxLogic_Runtime_Pop_ObjectScope(n);
                        return result;
             });

Again we want to implement this with tertiary operators.

[KAYLukas]

We do not need to check if the object is of the right type (at compile time): the as statement also does an implicit cast statement, which seems the most logical.

At runtime we need to ensure that we are allowed to do this, by using the instanceof keyword.