fix ambiguities

[putianyi889]

Aqua is set to check ambiguities.

• Solves #36

Related changes:

• Some tests change from NotANumber to ArgumentError #38
• Standalone +∞ now refers to RealInfinity(). Some +/- test results have changed accordingly, although not consistent. #39
• Support (fld|cld|div)(∞, x) where x<0
• Aqua tests are moved to the end of tests to make sure things work before fixing ambiguities.
• Support infinite Complex{float} + ∞
• min|max are set to follow Julia base convention, that is, min(x,y)=x and max(x,y)=y if x==y. This impacts ℵ₀ and ∞ specifically. #41

Not to do:

• Aim at full coverage. Most coverage losses are caused by ambiguity fix and are checked by Aqua.

[codecov[bot]]

Codecov Report

Patch coverage: 86.72% and project coverage change: -7.81 :warning:

Comparison is base (489b68b) 99.17% compared to head (95e4dbb) 91.37%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #40      +/-   ##
==========================================
- Coverage   99.17%   91.37%   -7.81%     
==========================================
  Files           2        6       +4     
  Lines         363      197     -166     
==========================================
- Hits          360      180     -180     
- Misses          3       17      +14     

Impacted Files	Coverage Δ
src/cardinality.jl	88.09% <0.00%> (-10.50%)	:arrow_down:
src/ambiguities.jl	52.63% <52.63%> (ø)
src/Infinities.jl	96.07% <66.66%> (-3.47%)	:arrow_down:
src/interface.jl	87.50% <87.50%> (ø)
src/algebra.jl	100.00% <100.00%> (ø)
src/compare.jl	100.00% <100.00%> (ø)

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