Performance improvements

Many thanks to @stevengj and @gdkrmr for their work on improving SHA.jl performance. As an example the time required to sha256() an 87MB file dropped from 0.85 seconds to 0.50 seconds on Julia 0.6.2.

Bump Compat requirement

v0.5.6

Bump Compat requirement

Performance improvements and 0.7 compatibility

More 0.7 compat (#52)

* `copy!()` -> `copyto!()`

* Quash more 0.7 compatibility bugs

* Require at least Compat 0.38

SHA3 optimizations

@dcjones contributed significant performance improvements to SHA3 (and some smaller benefits to SHA1/2 as well) while simultaneously reducing memory churn.

Previous performance on a 90MB file:

$ julia perf.jl ~/.julia/v0.6/BinaryBuilder/deps/downloads/rootfs-x86_64-apple-darwin14.tar.gz
read:      0.286516 seconds (6 allocations: 94.493 MiB, 32.75% gc time)
SHA-1:     0.569073 seconds (7 allocations: 960 bytes)
SHA2-256:   1.771765 seconds (6 allocations: 512 bytes)
SHA2-512:   1.289397 seconds (6 allocations: 656 bytes)
SHA3-256:   6.475997 seconds (728.55 k allocations: 88.935 MiB, 0.03% gc time)
SHA3-512:  13.375748 seconds (1.38 M allocations: 167.987 MiB, 0.02% gc time)

New performance on the same file:

$ julia perf.jl ~/.julia/v0.6/BinaryBuilder/deps/downloads/rootfs-x86_64-apple-darwin14.tar.gz
read:      0.203022 seconds (6 allocations: 94.493 MiB, 33.68% gc time)
SHA-1:     0.411811 seconds (7 allocations: 960 bytes)
SHA2-256:   1.460679 seconds (6 allocations: 512 bytes)
SHA2-512:   0.923359 seconds (6 allocations: 656 bytes)
SHA3-256:   1.568745 seconds (8 allocations: 992 bytes)
SHA3-512:   2.983240 seconds (8 allocations: 960 bytes)

Abstract out some hashing utilities

Used for MD5.jl

Performance and compatibility updates

sha256(open("foo")) now reads in chunks of a file at a time, rather than reading the entire thing into memory at once.

Compatibility updates

Cleanup and updated syntax. Thanks @musm for the attention to detail.

0.6+ compatibility release

Merge pull request #36 from Sacha0/fixdepwarns

fix depwarns under 0.7 and bump REQUIRE and CI to 0.6

v0.3.3: Merge pull request #35 from yuyichao/align

Fix wrong use of reinterpret

Julia 0.6 depwarning fixes

Merge pull request #31 from musm/patch-1

Update dep map! method