Promote CalcGraph's runner class into a native c++ feature

[Drakynfly]

The CalcGraph from the Demo project has a blueprint implementation for a DAG-style graph compiler. This should be nativized for general use, probably as part of a larger system of base tools for graph compilation.

[Drakynfly]

There should be several types of this:

1. A synchronous runner, that evaluates the graph in a single frame.
2. An asynchronous (but single-threaded) runner (using the ControlFlows plugin, most likely)
3. Some kind of multithreaded runner would be nice for complex tasks.