breaking abs2

[t-bltg]

Per #186 (review) and https://github.com/JuliaGraphics/ColorVectorSpace.jl#abs-and-abs2.

Should we also remove

ColorVectorSpace.jl/src/ColorVectorSpace.jl

Lines 541 to 549 in 35ddfef

	elseif exc.f === abs2 && length(argtypes) == 1
	C = argtypes[1]
	if C <: MathTypes
	print(io, "\nIt is ambiguous whether `abs2(::$C)` should return a real number ")
	print(io, "or a color object.")
	print(io, "\nYou can use `_abs2(c) = mapreducec(v->float(v)^2, +, 0, c)` ")
	print(io, "to get the value compatible with ColorVectorSpace v0.8 or earlier.")
	end
	end

?

cc @timholy or @johnnychen94.

[codecov]

Codecov Report

Base: 91.44% // Head: 91.41% // Decreases project coverage by -0.04% ⚠️

Coverage data is based on head (3aa32a4) compared to base (61e78ec).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #187      +/-   ##
==========================================
- Coverage   91.44%   91.41%   -0.04%     
==========================================
  Files           3        3              
  Lines         269      268       -1     
==========================================
- Hits          246      245       -1     
  Misses         23       23              

Impacted Files	Coverage Δ
src/ColorVectorSpace.jl	90.83% <100.00%> (-0.04%)	⬇️

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[johnnychen94]

Looks good to me but I'd leave it to @timholy to make the call since releasing this breaking change would require some extra maintenance efforts to bump the versions in downstream packages.

[t-bltg]

Rebased against master.

[t-bltg]

@timholy, do you think we can merge this PR and tag a new release ?

[timholy]

Sorry for the long delay, see #188

[timholy]

Folded into #188. Thanks a million, @t-bltg !