Significant rewrite of rendering pipeline to clean up abstractions and prepare to add postprocessing.

Rewrite the core Vulkan components into the form of a pipeline, with one source followed by a sequence of stages, each stage acting on a target (the frame to be displayed). This sets the stage for rendering pipelines including postprocessing, such as screenshots, recording, or GPU shader postprocessing, and cleans up the mess of dependencies and horrid interfaces I had made for myself. Also significantly improve all camera types and input handling to be framerate-independent.