Clean up - Githubissues

Some general things to clean up:

[x] Make error handling more consistent - maybe use an error handling library?
[x] Clean up the awkward code that avoids Seek from before I knew about Cursor
[ ] Address TODOs and FIXMEs
[x] Re-organize crate - tes3 and tes4 modules should be at the top with other stuff under them
[x] Use Clippy and rustfmt to improve code style
[x] Come up with a better way for handling attributes and skills
[x] Look for opportunities to reduce code duplication
[ ] Improve lazy documentation with examples
[ ] Write tests for things that don't have them
[ ] Make existing tests more focused

descawed / tesconvert