Fix build errors

[freddycansic]

The nightly feature proc_macro_span_shrink no longer exists but is being referenced by an old Cargo.lock file, resulting in a build error

error[E0635]: unknown feature `proc_macro_span_shrink`
  --> /home/freddy/.cargo/registry/src/index.crates.io-6f17d22bba15001f/proc-macro2-1.0.51/src/lib.rs:92:30
   |
92 |     feature(proc_macro_span, proc_macro_span_shrink)
   |                              ^^^^^^^^^^^^^^^^^^^^^^

For more information about this error, try `rustc --explain E0635`.
error: could not compile `proc-macro2` (lib) due to 1 previous error

Deleting Cargo.lock fixes this.
Added Cargo.lock to .gitignore for future commits.

[mautamu]

Hello, fellow adventurer @freddycansic!

Thank you for submitting this PR; I have resolved build errors (feel free to roll up if you would like) and requested review by @blackdragon2447 since Clippy suggested changing WindowRules to Rules which may be a breaking change if this is being used downstream.

[blackdragon2447]

I would prefer this stays as WindowRules instead Rules, because even though it is Window::WindowRules, both windows in that are completely disconnected, the window enum is referring to windows in the tui, while the WindowRules refer to LeftWM window rules.

[blackdragon2447]

Possibly remove the commented code fully if we're sure that we're not going to use it again.

[blackdragon2447]

I'd prefer if Cargo.lock stays on git, just to make sure builds stay consistent.

[blackdragon2447]

Sorry it took me so long to for the review, motivation is kinda all over the place.

[ChanceNCounter]

Review addressed on a fork as I wanted to build it =P