Fixed new argument name.
Fixed bug related to the new semantics of the before-last parameter of format_num.
Fixed bug (std_dev was a CallableFloat).
Fixed: old variable not used anymore.
Added test of the g format (with default precision 0).
Regression typo fixed.
Fixed the meaning of the precision for format_num().
Fixed the meaning of the prec parameter of format_num().
Better formatting.
Removed obsolete comment (see comments before robust_format()).
Removed obsolete comment.
Removed incorrect test (the % format type is like the f format type).
Added missing width handling (and exponent factoring/non-factoring) with the usual (+/-) notation.