double-converesion: add ARM 64 and OS X PPC compilation support (Florian Loitsch)
double-converesion: fix double-increment in Bignum::SubtractTimes; does not affect double-conversion from outside (Florian Loitsch)
update optional<> to N3672 spec, including "in_place" rather than "emplace"
Merge pull request #78 from chipdude/master

optional<> a la N3672