Improvements for drawing random numbers

[sethaxen]

This PR adds an optional AbstractRNG parameter to quatrand and nquatrand.

It also implements the necessary overloads to call methods like Base.rand(Quaternion{Float64}, 10) and Base.randn(Quaternion{Float64}, 10). These behave differently from quatrand, instead following the pattern set in base by Base.rand(<:Complex). Namely, rand draws each of the four real numbers from the interval [0,1]. randn draws from the proper Quaternion normal distribution, which requires a scaling by 1/sqrt(4) (as opposed to Complex which uses a scaling of 1/sqrt(2)).

[sethaxen]

@KristofferC can you review this or recommend someone who can?

[codecov]

Codecov Report

Merging #42 (3223d7b) into master (fd991e3) will increase coverage by 4.60%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #42      +/-   ##
==========================================
+ Coverage   39.18%   43.78%   +4.60%     
==========================================
  Files           3        3              
  Lines         342      354      +12     
==========================================
+ Hits          134      155      +21     
+ Misses        208      199       -9     

Impacted Files	Coverage Δ
src/DualQuaternion.jl	4.12% <100.00%> (+4.12%)	⬆️
src/Octonion.jl	10.00% <100.00%> (+10.00%)	⬆️
src/Quaternion.jl	80.79% <100.00%> (+3.33%)	⬆️

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[sethaxen]

The PR now adds also rand methods for Octonion and DualQuaternion, as well as a randn for Octonion.