Refactor Rust error handling

The Rust-side error handling of this crate is pretty bad because it's a mish-mosh of some error handling brought in from the `tiff` crate plus new error enums we defined ourselves.

I don't think we'll include this in our next release, but it would be nice to handle for 0.3.

Start by locating the Rust-side error handling and comparing the handling brought in from the `tiff` crate with the crate's own error enums. Map the current error paths before proposing a unified approach. Done means the error handling is consistent and suitable for consideration in the 0.3 release.

Written by the indexing model from the issue text.