Advent of code - Rusty w/ CLI

Lots of todos - might make the CLI generate better and handle multi years without changing main.rs, but idk, works well enough for now Adding README to make it easier to dust off after a year of not using it

Commands

• Run day / challenge

cargo run -- -d <day number> -c <challenge number>

• Generate day

cargo run -- -g -d <day number>
# Must add in main.rs 
# ...let handlers...

TODO

• Make every year / day / challenge runnable without code
• Automate year creation
• Automate input loading and saving (beyond getting the session token)
• CLI bootstrap itself