qoi 0.4.1

VERY fast encoder/decoder for QOI (Quite Okay Image) format
Documentation 
pub const QOI_OP_INDEX: u8 = 0x00; // 00xxxxxx
pub const QOI_OP_DIFF: u8 = 0x40; // 01xxxxxx
pub const QOI_OP_LUMA: u8 = 0x80; // 10xxxxxx
pub const QOI_OP_RUN: u8 = 0xc0; // 11xxxxxx
pub const QOI_OP_RGB: u8 = 0xfe; // 11111110
pub const QOI_OP_RGBA: u8 = 0xff; // 11111111

pub const QOI_MASK_2: u8 = 0xc0; // (11)000000

pub const QOI_HEADER_SIZE: usize = 14;

pub const QOI_PADDING: [u8; 8] = [0, 0, 0, 0, 0, 0, 0, 0x01]; // 7 zeros and one 0x01 marker
pub const QOI_PADDING_SIZE: usize = 8;

pub const QOI_MAGIC: u32 = u32::from_be_bytes(*b"qoif");

pub const QOI_PIXELS_MAX: usize = 400_000_000;