Shell2: 200× faster, persisted, multiplayer-native Shells

A terminal is a device that connects to a computer's front panel and allows users to input text and receive output. In the past, terminals were separate devices connected to computers via wires, but with the advent of microcomputers and graphical user interfaces, terminal emulators were developed to mimic the functionality of traditional terminals within computers. Replit is a platform that provides remote development environments in web browsers, and its terminal experience has been significantly improved through various technical changes such as eliminating string-byte conversions, avoiding stdio, and adhering to the zero overhead principle. Additionally, Shells have become persistent and multiplayable on Replit, allowing users to join their friends' Shell sessions and create new Shell panes without disrupting others' workflows.