Implementation of place for MIMO systems

[baggepinnen]

This PR implements the robust pole placement algorithm from

"Robust Pole Assignment in Linear State Feedback", Kautsky, Nichols, Van Dooren

This implementation uses "method 0" for the X-step and the QR factorization for all factorizations.

The current implementation works most of the time, but struggles with accuracy for some systems. A possible improvement is to switch "method 0" for any of "methods 2/3" from the paper for the X step.

[codecov]

Codecov Report

Merging #854 (6b0b9e3) into master (a82bf19) will not change coverage.
The diff coverage is n/a.

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##           master     #854   +/-   ##
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  Coverage   92.72%   92.72%           
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  Files           5        5           
  Lines         330      330           
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  Hits          306      306           
  Misses         24       24           

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