Replacement for snprintf

[Walter Bright]

Replacing snprintf for floating point is very challenging, because:

1. people have been improving snprintf for decades
2. people expect precision and performance
3. the standard is snprintf, any credible implementation must be the same or better

To that end, you'll need to be familiar with the following:

754-2019 IEEE Standard for Floating Point Arithmetic
https://ieeexplore.ieee.org/document/8766229

Printing Floating-Pointer Numbers Quickly and Accurately with Integers
https://www.cs.tufts.edu/~nr/cs257/archive/florian-loitsch/printf.pdf

Printing Floating-Point Numbers
https://ranjitjhala.github.io/static/fp-printing-popl16.pdf

Ryu Fast Float To String Conversion
https://dl.acm.org/citation.cfm?id=3192369

https://github.com/ulfjack/ryu
http://www.zverovich.net/2019/02/11/formatting-floating-point-numbers.html
https://news.ycombinator.com/item?id=20181832

Jonathan Marler's D implementation of ryu:
https://github.com/dragon-lang/mar/blob/master/src/mar/ryu.d

For historical interest, here's DMC's version, which was state of the art in the 
1980's:

https://github.com/DigitalMars/dmc/blob/master/src/core/floatcvt.c