The provided implementation tries to fix positions for the group
separator.
In case of scientific notation it can also converts the value to
normalized form.
It uses QLocale::FloatingPointShortest internally to convert the
double value back to string, so the number of decimals may change
after calling this method.
Change-Id: I963bc5f97b653e2bb912f4b95b09a4d1ee201e7f
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>