Preloading revamp

• Revamped preloading to be more performant. NEU has a preloading system where it loads textures of skull items into RAM prematurely so that your game does not freeze for a split second when opening backpacks/echest or the NEU item list, but this preloading process eats your frametimes when you first join skyblock for about 2.5 minutes till the preloading is finished. This revamp makes this preloading process start earlier, finish faster and affect frame times less.