string date to parse
format list - i18 tranlation by default
allowed format specifiers:
d: date (1 or 2 digits)
D: date (2 digits)
m: month (1 or 2 digits)
M: month (2 digits)
y: year (2 to 4 digits)
Y: year (2 digits)
YY: year (4 digits)
h: hours (1 or 2 digits)
H: hours (2 digits)
i: minutes (1 or 2 digits)
I: minutes (2 digits)
s: seconds (1 or 2 digits)
S: seconds (2 digits)
parse a date according to the given format