fix ambiguities

[putianyi889]

Aqua is set to check ambiguities.

• Solves Is there a reason to skip ambiguity test in Aqua? #36

Related changes:

• Some tests change from NotANumber to ArgumentError NotANumber vs ArgumentError #38
• Standalone +∞ now refers to RealInfinity(). Some +/- test results have changed accordingly, although not consistent. Infinity vs RealInfinity() #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. Comparing ℵ₀ and ∞ #41

[codecov]

Codecov Report

Attention: Patch coverage is 99.11504% with 1 line in your changes missing coverage. Please review.

Project coverage is 96.92%. Comparing base (ea87cbe) to head (5ca6995).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
src/interface.jl	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #40      +/-   ##
==========================================
- Coverage   99.19%   96.92%   -2.28%     
==========================================
  Files           2        6       +4     
  Lines         373      195     -178     
==========================================
- Hits          370      189     -181     
- Misses          3        6       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[putianyi889]

A crucial line somehow loses coverage. Removing the line results in failed tests. I've added a note to the line.