Implement traits correctly

[sostock]

The old implementation works correctly for Quantity{T} when T is a number type defined in Base, but not when T is defined elsewhere and has a custom implementation of these traits.

[codecov-io]

Codecov Report

Merging #407 (0d50f2a) into master (b32de8d) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #407      +/-   ##
==========================================
+ Coverage   80.41%   80.48%   +0.06%     
==========================================
  Files          15       15              
  Lines        1195     1194       -1     
==========================================
  Hits          961      961              
+ Misses        234      233       -1     

Impacted Files	Coverage Δ
src/range.jl	79.54% <100.00%> (+1.76%)	⬆️

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[giordano]

Any test relevant for this change?

[sostock]

Any test relevant for this change?

I’ll add one.

[sostock]

I added tests, utilizing the Num type already defined in the test suite.