This commit removes some clippy warnings (to advance #45) by doing the following:
- replace usage of `mem::uninitialized()` with `MaybeUninit`
- replace usage of `nix::libc::{uint64_t, int32_t}` with `{u64, i32}`
- replace functions inside of `Option::ok_or` with `Option::ok_or_else`
- replace functions inside of `Result::unwrap_or` with `Result::unwrap_or_else`
- replace occurrences of pass-by-reference with pass-by-value when
appropriate
- replace unused variables in pattern-matching with wildcards
- replace `match` expressions that have only one case with `if let`
expressions
- replace UpperCamelCase names of consts with SCREAMING_SNAKE_CASE
- remove `clone()` on types that implement Copy
- remove redundant imports
- remove `fn main()` from doctests
- remove let binding for variables that are returned afterwards
With the new XkbConfig struct, it is now easier to just use xkbcommon's
default configuration, by moving the xkbcommon specific options into a
struct with according documentation.
Additionally, anvil now uses xkbcommon's defaults with all backends
(previously, the winit backend had a hardcoded french keyboard layout).