CHANGES:

• Add eighth-order finite difference approximation
• Fix bug in Jacobian with different input/output dimensions (#557)
• Fix bug in nested grads (#558)
• Update to ocamlformat.0.16.0 (thanks @gpetiot #556)
• Add get_fancy to AD
• Check input and output type of diff operation
• Fix bug in build_info of aiso pattern in AD
• Implement split forward mode and check max tag of build_info
• Add initial implementation of fft2 and ifft2
• Add nonsymmetric qs suppport for continuous and discrete time lyapunov gradients
• Improve care and dare operations in AD
• Improve forward mode efficiency for sylv, clyap and dlyap operations in AD