Fix readstring depwarns

REQUIRE

@@ -1,4 +1,4 @@
-julia 0.4
+julia 0.5
 BenchmarkTools 0.0.7
-Compat 0.19.0
+Compat 0.30.0
 JLD

src/io/IOBenchmarks.jl

@@ -28,7 +28,7 @@ g = addgroup!(SUITE, "read", ["buffer", "stream", "string"])
 testbuf = IOBuffer(randstring(RandUtils.SEED, 10^4))
 
 g["read"]       = @benchmarkable perf_read!($testbuf)
-g["readstring"] = @benchmarkable readstring($testbuf)
+g["readstring"] = @benchmarkable read($testbuf, String)
 
 #################################
 # serialization (#18633, #7893) #

src/problem/ProblemBenchmarks.jl

@@ -81,7 +81,7 @@ include("JSONParse.jl")
 
 g = addgroup!(SUITE, "json", ["parse", "closure"])
 
-jstr = readstring(joinpath(PROBLEM_DATA_DIR, "test.json"))
+jstr = read(joinpath(PROBLEM_DATA_DIR, "test.json"), String)
 
 g["parse_json"] = @benchmarkable JSONParse.perf_parse_json($(jstr))
 

src/problem/SpellCheck.jl

@@ -24,7 +24,7 @@ function train(features)
     return model
 end
 
-const NWORDS = train(words(readstring(joinpath(PROBLEM_DATA_DIR, "norvig_spellcheck.txt"))))
+const NWORDS = train(words(read(joinpath(PROBLEM_DATA_DIR, "norvig_spellcheck.txt"), String)))
 
 function edits(word::AbstractString)
     splits     = [(word[1:i], word[i+1:end]) for i=0:length(word) ]

src/shootout/k_nucleotide.jl

@@ -68,7 +68,7 @@ function perf_k_nucleotide()
             break
         end
     end
-    data = collect(readstring(input))
+    data = collect(read(input, String))
     # delete the newlines and convert to upper case
     i, j = 1, 1
     while i <= length(data)

src/shootout/regex_dna.jl

@@ -32,7 +32,7 @@ const subs = [
 
 function perf_regex_dna()
     infile = joinpath(SHOOTOUT_DATA_PATH, "regexdna-input.txt")
-    seq = readstring(infile)
+    seq = read(infile, String)
     l1 = length(seq)
 
     seq = replace(seq, r">.*\n|\n", "")