Summer / Daylight Savings time support

phpBB 3 introduces support for daylight savings (aka summer) time, which is great. my report is between a bug and a feature request.

as far as I could test, the converter will simply copy the users timezone and assume daylight savings is OFF. this results in correct time displayed, but wrong timezone + daylight savings settings, when the conversion process takes place when daylight savings time is in effect. like right now.

if the conversion process takes places during daylight savings time in effect, the converter should substract 1 to the time zone, and set daylight savings time ON.

an example to be even more clear. a user from Central Europe with time zone GMT+2 in phpBB 2 will be converted to "[UTC + 2] Eastern European Time, Central African T" and DST off. it should rather be converted to "[UTC + 1] Central European Time, West African Time" with DST on.

a checkbox option could be presented to the admin during the conversion process, to activate this trick (that is: substract 1 to timezone and activate DST). the default value would be to check this box when DST is in effect, and not to check it otherwise.