typo fixes all over the place

found and semi-manually replaced by using:
 codespell -L mut -L crate -i 3 -w

Mostly in comments, but also email notification and two occurrences
of misspelled  'reserved' struct member, which where not used and
cargo build did not complain about the change, soo ...

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/tape/changer/mtx/mod.rs

@@ -1,4 +1,4 @@
-//! Wrapper around expernal `mtx` command line tool
+//! Wrapper around external `mtx` command line tool
 
 mod parse_mtx_status;
 pub use parse_mtx_status::*;