Inverse and determinant trait for ndarray Array2

When creating some kalman filter code there was a need for Matrix inversion. Installing external code to calculate inverses was clunky and painful. Hence this little trait. It's 'reasonably' quick for small Matrices, a dedicated library, even on a CPU is ~8x faster for bigger Matrices.

If your priority is ease of installation, pure Rust and portability then this might be useful.

Simple reference with:

use ndarray-inverse::Inverse;

Add a cargo dependency too:

ndarray-inverse = "*"