Skin system overhaul

[BenCheung0422]

Is your feature request related to a problem? Please describe. The current skin system is very lack of extensibility, also the clothing system does not fit the skin system really well. If there is rendering on armors, changes are still required to make it compatible. Related issues: #295 and #382.

Describe the solution you'd like There have 2 options on file system: using a single bigger PNG file (like Minecraft), or using a zip/custom file containing various settings of a skin, also including variable sizes of PNG files (like Osu!). For implementation of a skin based on pixels, separating and marking standards for parts of a skin like Minecraft limiting the pixels in captures. With this, movable parts of skin might also be possibly implemented, and separating the skin into pieces.