Third attempt for SUM

[Ilya Yaroshenko via Digitalmars-d]

Hi all,

Advanced summation algorithms [3] from Mir project [1] are ready 
to be merged to Phobos. Many thanks to Walter Bright for the new 
Dlang floating point semantic [2].

Best regards,
Ilya

1. https://github.com/libmir/mir
2. https://github.com/dlang/dmd/pull/6247
3. https://github.com/dlang/phobos/pull/4896