make random_state sklearn compliant

[rpreen]

Currently random_state can only be an integer value where <= 0 uses the system time and > 0 sets the seed.

This PR makes Python library random_state sklearn compliant:

• random_state with an integer value < 0 uses system time as seed;
• random_state with an integer value >= 0 will set the seed;
• Python API maps random_state = None to -1 and uses system time as seed;

Note that are still some situations where setting the random number seed will not result in reproducible results, such as when using parallel processing and random numbers are used during forward propagation of neural nets (such as dropout layers.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (dc9aea8) 61.89% compared to head (9ef69f6) 61.89%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #97   +/-   ##
=======================================
  Coverage   61.89%   61.89%           
=======================================
  Files          62       62           
  Lines        8894     8894           
  Branches     1073     1073           
=======================================
  Hits         5505     5505           
  Misses       3389     3389           

Files	Coverage Δ
xcsf/param.c	84.49% <100.00%> (ø)

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
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100.0% Coverage
0.0% Duplication