The first date format string to compare
The second date format string to compare
A negative value if formatA is before formatB, a positive value if formatA is after formatB, or 0 if they are the same
Priority order:
Y-M-D variations (replacing "-" with ".", ",", "/", ", ", " ", etc.)D-M-Y variationsM-D-Y variationsY-M variationsM-Y variationsM-D variationsD-M variationsWithin each category, formats are sorted by separator:
-./,,  then by format specificity (M2/D2 before M1/D1)
Compare two date format strings for sorting purposes.