mapm 5

[albertmcchan <albertmcchan@...>]

I had mapm-src.7z posted in github about a year ago

https://github.com/achan001/dtoa-fast

mapm has a feature that mpfr and decNumber does not have:
Do exact multiply (infinite precision), not just arbitrary precision.

mapm were used for strtod_fast() to handle close to half-way cases,
and dtoa_fast() to produce correct rounded decimal string.

I had later added gmp as another option (now, default = gmp)