user confusion, so specify it directly, i.e. change "3" to "3;0".
In this style "3;" must not cause repeating (converted to \3, CHAR_MAX, \0)
NOTE: still no proper conversion done in localeconv()
repeated forever according to SUSv2
Remove "0;0" - \0 means not "no grouping" but repeat forever previous char,
and added automatically. Empty string could be parsed later into CHAR_MAX
(real "no grouping") by localeconv()