Fix Julia parseintperf after quick replace

[Enet4]

Fixes #21

[johnfgibson]

The current code in git is correct for julia-0.7; this PR would revert it back for julia-0.6. It was a call to hex in the python code perf.py that inadvertantly got swept up in a global hex -> string replace meant for Julia, not the other way around.

function parseintperf07(t) # what's currently in git, works on julia-0.7
    local n, m
    for i=1:t
        n = rand(UInt32)
        s = string(n, base = 16)
        m = UInt32(parse(Int64, s, base = 16))
        @assert m == n
    end
    return n
end

function parseintperf06(t)  # the proposed PR, works on 0.6, shows deprecation on 0.7
    local n, m
    for i=1:t
        n = rand(UInt32)
        s = hex(n)
        m = UInt32(parse(Int64, s, 16 ))
        @assert m == n
    end
    return n
end

julia-0.7-beta2.45

julia> parseintperf07(1000)
0x4a89aabf

julia> parseintperf06(1000)
┌ Warning: `hex(n)` is deprecated, use `string(n, base=16)` instead.
│   caller = parseintperf06(::Int64) at parseintperf.jl:16
└ @ Main ~/scratch/julia/parseintperf.jl:16
┌ Warning: `parse(T::Type{<:Integer}, s, base)` is deprecated, use `parse(T, s, base=base)` instead.
│   caller = parseintperf06(::Int64) at parseintperf.jl:17
└ @ Main ~/scratch/julia/parseintperf.jl:17
0x599d7969

julia> versioninfo()
Julia Version 0.7.0-beta2.45
Commit 91c2da8acb (2018-07-19 07:13 UTC)
Platform Info:
  OS: Linux (x86_64-suse-linux)
  CPU: Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, skylake)

It would probably be worthwhile to make the microbenchmarks were 0.6/0.7 compatible. There are a few differences in

• packages to load with using
• mean and std moving to Statistics package
• hex and string

I think that might be it. I haven't used Compat.jl yet, but it can't be too complicated. There are no performance hits with compatibility, right?

[StefanKarpinski]

Compat is pretty straightforward: basically, write code for 0.7 and sprinkle @compat calls where necessary to make it work on 0.6. No performance issues in general. I would also be surprised about much in the microbenchmarks being different between the versions.