Speed up trie construction by factor of ~3.

Take advantage of word-at-once checking for slices of bit-packed
arrays in the trie.
std.digest.sha: disable SSSE3 for SHA because it has unsupported calling convention
std.format, std.math: workarounds for different behaviour of sprintf
std.conv: workarounds for different behaviour of strtold
std.math: disable unittests for exp2f and exp2l
std.math: fix lrint(real), disable tmpfile test
std.process: seek to end of file before trying to append to it from another process
std.process: do not try to terminate an invalid process handle
win64.mak: disable COMDAT folding for release build
Merge pull request #1411 from rainers/win64_enable_unittests

do not skip unittests for Win64
[Trivial] Fix documentation typos in std.algorithm
[Trivial] Fix documentation typos in std.array
Merge pull request #1973 from yazd/fix-typos

[Trivial] Fix documentation typos
Merge pull request #1969 from blackwhale/faster-trie-build

std.uni - speed up Trie construction by factor of ~3
[Trivial] Fix documentation typos
Merge pull request #1974 from yazd/fix-typos

[Trivial] Fix documentation typos in Phobos