Added benchmarks for static arrays

[chriselrod]

This is the file I used to produce the benchmark versus StaticArrays shown here.

The OctavianStatic benchmarks are matmul! called on StaticArrays.MArray, and OctavianDynamic are on the base Matrix type without static size information.

On the computer I benchmarked on, multithreading starts at 48x48 for Float64 currently, but apparently not for the statically sized case, since it seems to have been single threaded. I'll have to check why not.

[codecov]

Codecov Report

Merging #51 (8d66bb5) into master (7fa8e03) will increase coverage by 1.39%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #51      +/-   ##
==========================================
+ Coverage   40.97%   42.37%   +1.39%     
==========================================
  Files          12       12              
  Lines         715      715              
==========================================
+ Hits          293      303      +10     
+ Misses        422      412      -10     

Impacted Files	Coverage Δ
src/init.jl	60.00% <0.00%> (-10.00%)	⬇️
src/matmul.jl	41.56% <0.00%> (-0.42%)	⬇️
src/macrokernels.jl	22.51% <0.00%> (+6.80%)	⬆️

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