Many improvements

[uwx]

• Use log4j instead of System.out
• Make python client app an HTTP server instead
• Support setting model
• Improve memory footprint of item textures
• Cache rendered item meshes
• Reduce overhead of writing items.json and recipes.json
• Create config folder by default if not exists on first launch
• Improve handling of malformed JSON output returned by the conversation API
• Fix some threading mishaps
• Fix issues where sometimes items would never render their generated image
• Use modern java HttpClient
• Encode generation results directly in item's NBT for use later (maybe useful for multiplayer compatibility?)
• Use JSON to POCO deserialization instead of manually wrestling JsonObjects