Use Base.Ordering for heap, and other performance changes

[milesfrain]

Local preview of change to collect benchmarking results.
Upstreamed in JuliaCollections#547

[milesfrain]

Travis got confused. Here's the link to the passing job https://travis-ci.org/milesfrain/DataStructures.jl/builds/590285275

[milesfrain]

Local benchmark results generated with:

git branch -f baseline HEAD~
julia --project=benchmark -e '
    using Pkg; Pkg.instantiate();
    include("benchmark/runjudge.jl");
    include("benchmark/pprintjudge.jl");'

                                                             ID  time ratio memory ratio
––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– ––––––––––– ––––––––––––
       ["heap", "BinaryHeap", "make", "Float64", "10^1", "Min"] 0.40 (5%) ✅    1.00 (1%)
       ["heap", "BinaryHeap", "make", "Float64", "10^3", "Min"] 0.69 (5%) ✅    1.00 (1%)
         ["heap", "BinaryHeap", "make", "Int64", "10^1", "Min"] 0.29 (5%) ✅    1.00 (1%)
         ["heap", "BinaryHeap", "make", "Int64", "10^3", "Min"] 0.60 (5%) ✅    1.00 (1%)
        ["heap", "BinaryHeap", "pop", "Float64", "10^1", "Min"] 0.93 (5%) ✅    1.00 (1%)
          ["heap", "BinaryHeap", "pop", "Int64", "10^1", "Min"] 0.87 (5%) ✅    1.00 (1%)
       ["heap", "BinaryHeap", "push", "Float64", "10^1", "Min"] 0.94 (5%) ✅    1.00 (1%)
       ["heap", "BinaryHeap", "push", "Float64", "10^3", "Min"] 0.90 (5%) ✅    1.00 (1%)
         ["heap", "BinaryHeap", "push", "Int64", "10^1", "Min"] 0.94 (5%) ✅    1.00 (1%)
         ["heap", "BinaryHeap", "push", "Int64", "10^3", "Min"] 0.86 (5%) ✅    1.00 (1%)
           ["heap", "BinaryMaxHeap", "make", "Float64", "10^1"] 1.12 (5%) ❌    1.00 (1%)
           ["heap", "BinaryMaxHeap", "make", "Float64", "10^3"] 0.73 (5%) ✅    1.00 (1%)
            ["heap", "BinaryMaxHeap", "pop", "Float64", "10^3"] 0.94 (5%) ✅    1.00 (1%)
           ["heap", "BinaryMaxHeap", "push", "Float64", "10^1"] 0.93 (5%) ✅    1.00 (1%)
           ["heap", "BinaryMaxHeap", "push", "Float64", "10^3"] 0.93 (5%) ✅    1.00 (1%)
           ["heap", "BinaryMinHeap", "make", "Float64", "10^1"] 1.14 (5%) ❌    1.00 (1%)
           ["heap", "BinaryMinHeap", "make", "Float64", "10^3"] 0.75 (5%) ✅    1.00 (1%)
            ["heap", "BinaryMinHeap", "pop", "Float64", "10^1"] 0.89 (5%) ✅    1.00 (1%)
           ["heap", "BinaryMinHeap", "push", "Float64", "10^3"] 0.91 (5%) ✅    1.00 (1%)
["heap", "MutableBinaryHeap", "make", "Float64", "10^1", "Min"] 0.45 (5%) ✅    1.00 (1%)
  ["heap", "MutableBinaryHeap", "make", "Int64", "10^1", "Min"] 0.36 (5%) ✅    1.00 (1%)
                 ["heap", "nlargest", "a=rand(10^4)", "n=10^2"] 0.49 (5%) ✅  0.57 (1%) ✅
                ["heap", "nsmallest", "a=rand(10^4)", "n=10^2"] 0.59 (5%) ✅  0.57 (1%) ✅

Full log available here:
https://gist.github.com/milesfrain/d6df9803e0bacac97eb551dd02d04e7b