consider using deku for serializing/parsing structs

[cosmicexplorer]

Problem

#93 is super cool, but adds a lot of boilerplate parsing code. This has been abstracted into the Block trait from that PR, but there's a lot of tricky bits with endianness, and it's been taking lots time and effort to become mergeable.

Proposed Solution

Deku (https://github.com/sharksforarms/deku) performs the process of byte-level serialization, and has specific handling for endianness. It also recently implemented std::io::{Read,Write} traits (see https://docs.rs/deku/latest/deku/#read-supported), which should cover the entire functionality of the Block trait and the {from,to}_le! macros introduced in #93.

Expected Result

We may be able to remove a lot of boilerplate code while retaining (or maybe exceeding?) the performance benefits of #93 by delegating that work to the deku crate.