Some benchmarks and comparisons

[AtheMathmo]

It would be valuable to benchmark rulinalg. It would also be great to do comparisons against other libraries, both utilizing LAPACK and standalone - to see how well rulinalg holds its own.

Things to benchmark:

• Matrix Multiplication
• Matrix Inversion
• Eigen Decomposition
• Singular Value Decomposition

It would be good to show rulinalg vs. LAPACK (or some library consuming, i.e. scipy). Even just having these benchmarks without a direct comparison would be very valuable.

It would be nice to produce a BENCHMARKS.md file in the root project directory. I see this file containing a table (or set of tables) with the details of the machine used to produce the table clearly visible. The table should have rows per function benchmarked with columns for each framework tested (rulinalg in first column for each).

[AtheMathmo]

I'm labeling this as easy to highlight that there is room for some really valuable and lightweight contributions here.

Most of the functionality is not bench-marked right now which leaves us open to performance regressions. It would be greatly appreciated to add simple benchmarks to any functionality which is currently missing them (most are...)