Sudoku solver library for Rust

This library provides a very simple backtracking algorithm for solving sudoku puzzles.

Example

```rust use sudoku_solver::*;

fn main() { let board = Board::from(&[ [0, 2, 0, 0, 0, 0, 0, 0, 0], // row 1 [0, 0, 0, 6, 0, 0, 0, 0, 3], // row 2 [0, 7, 4, 0, 8, 0, 0, 0, 0], // row 3 [0, 0, 0, 0, 0, 3, 0, 0, 2], // row 4 [0, 8, 0, 0, 4, 0, 0, 1, 0], // row 5 [6, 0, 0, 5, 0, 0, 0, 0, 0], // row 6 [0, 0, 0, 0, 1, 0, 7, 8, 0], // row 7 [5, 0, 0, 0, 0, 9, 0, 0, 0], // row 8 [0, 0, 0, 0, 0, 0, 0, 4, 0], // row 9 ]);

println!("Puzzle:\n{}\n", board);

if let Some(solution) = solve(&board) {
    println!("Solution:\n{}\n", solution);
} else {
    println!("No solution found.");
}

} ```