Removes code warnings
Removes code warnings

Clippy warnings are only stylistic and so shouldn't change behaviour.

mindriot101/rust-fitsio,mindriot101/rust-cfitsio,mindriot101/rust-fitsio,mindriot101/rust-fitsio,mindriot101/rust-fitsio,mindriot101/rust-fitsio,mindriot101/rust-cfitsio