Log Message:
p5-Math-Matrix: update to 0.91.

Add LICENSE.

0.91 2020-08-09

 * Ensure a recent version of Math::Complex in the test files that use that
   module. Math::Complex didn't support any way of cloning/copying
   Math::Complex objects before version 1.57.

0.9 2020-08-07

 * Fix typos in POD and add more documentation and examples.

 * Extended new() to handle empty matrices and allow the matrix to be specified
   as a single argument.

 * Improve code so subclassing works better.

 * Add many new tests to confirm existing and new behaviour.

 * Misellaneous modernizations.

 * This release closes CPAN RT ##104334 and #109353.