Avoid overriding function in Base since v1.2

[nickrobinson251]

• This adds a version check to function we define that were since added to Base.
• Enables CI for 1.1 and 1.2 (these functions were added to Base in 1.2)
• ...and wraps the tests in a testset (this can be reverted / a separate PR if you prefer -- i just noticed it when running tests)

Warnings fixed by this change (in v"1.2.0-rc2.0"):

julia> using AcceleratedArrays
[ Info: Recompiling stale cache file /Users/nick/.julia/compiled/v1.2/AcceleratedArrays/mcm9V.ji for AcceleratedArrays [44e12807-9a19-5591-91cf-c1b4fb89ce64]
WARNING: Method definition <(Any) in module Base at operators.jl:1015 overwritten in module AcceleratedArrays at /Users/nick/.julia/packages/AcceleratedArrays/vPA4c/src/predicates.jl:53.
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition <=(Any) in module Base at operators.jl:989 overwritten in module AcceleratedArrays at /Users/nick/.julia/packages/AcceleratedArrays/vPA4c/src/predicates.jl:54.
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition >(Any) in module Base at operators.jl:1002 overwritten in module AcceleratedArrays at /Users/nick/.julia/packages/AcceleratedArrays/vPA4c/src/predicates.jl:55.
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition >=(Any) in module Base at operators.jl:976 overwritten in module AcceleratedArrays at /Users/nick/.julia/packages/AcceleratedArrays/vPA4c/src/predicates.jl:56.
  ** incremental compilation may be fatally broken for this module **

WARNING: Method definition !=(Any) in module Base at operators.jl:963 overwritten in module AcceleratedArrays at /Users/nick/.julia/packages/AcceleratedArrays/vPA4c/src/predicates.jl:57.
  ** incremental compilation may be fatally broken for this module **

[iamed2]

Useful for https://github.com/invenia/IndexedDims.jl :)

[codecov-io]

Codecov Report

Merging #3 into master will increase coverage by 0.42%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master       #3      +/-   ##
==========================================
+ Coverage    72.7%   73.13%   +0.42%     
==========================================
  Files          11       12       +1     
  Lines         403      402       -1     
==========================================
+ Hits          293      294       +1     
+ Misses        110      108       -2

Impacted Files	Coverage Δ
src/predicates.jl	82.75% <0%> (ø)	⬆️
src/AcceleratedArray.jl	50% <0%> (-7.15%)	⬇️
src/AcceleratedArrays.jl	100% <0%> (ø)
src/SortIndex.jl	96.96% <0%> (+4.21%)	⬆️

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[nickrobinson251]

ping @andyferris :)

[andyferris]

Awesome - nice work. thanks @nickrobinson251! (Sorry for the delay)