Apply Spigot's patches

Filter Invalid Names https://github.com/SpigotMC/Spigot-Server/commit/3cb931a5529a70fda7ed2c90909dbf2ca66224da
Plug World Unload Memory Leak https://github.com/SpigotMC/Spigot-Server/commit/97e5a3bfdd94735747fad1bae3797eab210cde8e
Silence End of Stream Errors https://github.com/SpigotMC/Spigot-Server/commit/93439203ebb4ab6c7d73c81813aacc82aa30469d
Fix for double [ and ] symbols in fakeplayers names