This change updates the source structure of the OpenDC frontend to
follow the page structure.

This change updates the topology view in the OpenDC frontend to isolate
the world coordinate space. This means that zooming and panning should
not affect the coordinates in world space (but only in camera space). In
turn, this allows us to remove the dependency on Redux for the camera
controls.

This change updates the project structure to become flattened.
Previously, the simulator, frontend and API each lived into their own
directory.

With this change, all modules of the project live in the top-level
directory of the repository. This should improve discoverability of
modules of the project.