Fix warnings in rust 1.90.0

Cleanup Cargo.toml

Update pixels dependency to 0.15

Merge pull request #13 from hackmad/linux-gui

Switch from tao to winit in order to support previews on Linux

Add debug trait for the parser structs

Update USAGE

Add CLI option to show preview window

Merge pull request #12 from hackmad/gui

Add demo of GUI

Support preview window resize / redraw for each PBRT file being rendered in turn

Refactor the code to merge film tile and image save

Add a GUI window with tao + pixels to display render progress

Replace OnceLock with LazyLock

Update dependency versions