fn reshape_mut(&mut self, (r, c): (usize, usize), shape: Shape) {
        assert_eq!(self.row * self.col, r * c);
        self.row = r;
        self.col = c;
        self.shape = shape;
    }
Resize matrix (Mutable)

```
#[macro_use]
extern crate peroxide;
use peroxide::fuga::*;

fn main() {
let mut a = ml_matrix("1 2 3;4 5 6"); // ml_matrix has shape `Row`
a.reshape_mut((3, 2), Row);
assert_eq!(a, ml_matrix("1 2;3 4;5 6"));
a.reshape_mut((3, 2), Col);
assert_eq!(a, ml_matrix("1 4;2 5;3 6"));
}
```
src/traits/sugar.rs