Add and resolve clippy lints to prevent unwrap and expect functions

[quexeky]

Could also potentially include preventing panic!(), although there may be some use for panic!() still:

#![deny(
    clippy::unwrap_used,
    clippy::expect_used,
    clippy::panic
)]

[DecDuck]

I think we should just use .expect() when we want to crash. For a non-library application like this, panicking when we want to hard crash is the way to go.