Trigonometric functions

[mihaubuhai]

Trig functions

This pull request provides implementations (generically) for the basic trig functions: sine, cosine, tangent and cotangent.

Those generic functions come with the condition for the argument (value for which the trig function will be evaluated) / that particular data type to implement Into<f64> and Copy traits.
Also my last 2 functions have been changed to generic types: least_square_aprox and logarithm

The trig functions sine and cosine are evaluated using their MacLaurin expansion, which is very much similar and that's the purpose of the 'template' function in trig_functions.rs file.
Because those trig functions are related to each other, their implementation is found in the same file, trig_functions.rs

[codecov-commenter]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (c522e60) 94.52% compared to head (bd11075) 94.56%.
Report is 1 commits behind head on master.

Files	Patch %	Lines
src/math/logarithm.rs	66.66%	4 Missing ⚠️
src/math/least_square_approx.rs	96.55%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #643      +/-   ##
==========================================
+ Coverage   94.52%   94.56%   +0.03%     
==========================================
  Files         282      282              
  Lines       22606    22744     +138     
==========================================
+ Hits        21369    21508     +139     
+ Misses       1237     1236       -1     

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[siriak]

Looks good, thanks!