The new editor is being designed to be flexible enough to work with any game, so it can be used for modding as well as game development with our new 3D engine. Each project has configurable settings that can be used to handle what the editor actually does when you run the game. In the case of a game like Quake, this will involve running a few executables to first compile the map you are working on into a BSP structure, then perform lightmaps and pre-calculate visibility.
You can also set up your own custom workflow to automatically convert textures and models, using either the import / export capabilities of the editor plugins, or an external executable. In Leadwerks, this was all hard-coded with the FBX to MDL converter and a few other converters, but in the new editor it's totally configurable.