[jsxilinx]: Major refactoring. Dedicated the JSXilinx folder for JS-based Xilinx experiments. Current JSXilinx is now Watertank, and is an experiment within JSXilinx. Separated JSON-described 3D models and their textures into their own folders. Certain JS scripts such as the WorldLoader.js and Widget.js, which are somewhat generic, now belong in a libs folder within the JSXilinx folder.