Single and Double numeric formats may not round-trip successfully using CsvWriter

[glopesdev]

We have detected that Single (32-bit float) or Double (64-bit float) recorded into CSV may not round-trip successfully in the microsecond range for sufficiently large numbers. We have traced down the problem to the formatting defaults of the General Format Specifier of the ToString method, which use G7 and G15 respectively as max precision defaults on .NET framework.

In the recommendations for using the Round-trip format specifier the recommendation is to use G9 and G17 respectively for maximum fidelity.