CB7 libraries for Rust

• sevenz-rust2 reads and writes 7z in pure Rust. No system library, so it builds anywhere. Apache-2.0.
• compress-tools binds the system libarchive and reads 7z, RAR, ZIP and TAR with the same functions. Read only.

• compress-tools Read CB7 (7z) comic book archives in Rust with compress-tools, a libarchive binding: list pages in natural order, extract one page or the cover.
• sevenz-rust2 Read and write CB7 (7z) comic book archives in Rust with sevenz-rust2: pure Rust. List pages in natural order, read all pages in one pass, extract the cover.