Derive macros for reading and writing

[Antikyth]

A.k.a. serialize and deserialize traits. Might want to do #3 first?

[Antikyth]

This is code that can derive implementations of cornflakes::Readable and cornflakes::Writable.

Examples

#[derive(Readable, Writable)]
pub struct CharInfo {
    pub left_side_bearing: i16,
    pub right_side_bearing: i16,
    pub character_width: i16,
    pub ascent: i16,
    pub descent: i16,
    pub attributes: u16,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut buffer1: Vec<u8> = vec![];

    let char_info = CharInfo {
        left_side_bearing: 0,
        right_side_bearing: 0,
        character_width: 10,
        ascent: 0,
        descent: 0,
        attributes: 0,
    };

    buffer1.write(char_info)?;

    let mut buffer2: Vec<u8> = vec![];

    buffer2.write_i16(0)?;
    buffer2.write_i16(0)?;
    buffer2.write_i16(10)?;
    buffer2.write_i16(0)?;
    buffer2.write_i16(0)?;
    buffer2.write_u16(0)?;

    assert_eq!(buffer1, buffer2);
}

[Antikyth]

Completed in #31