Publish the crate

[alnyan]

As the crate might be useful for other rust-osdev'ers, I want to get it published on crates.io. There are several problems that need to be solved before that happens, though:

• The crate should work with a release version of acpi-repo crates
• All TODOs and todo!()s (at the moment of Initial commit) need to be gone
• Provide at least some documentation to simplify the integration process
• Allow user-provided handlers for fixed events ([Event] Cleanup handling of events #2)
• (Possibly) provide an example of a full acpi_system::Handler implementation with SCI handling