Change to DST one week late?

[matrices-zzz]

This year and last year I've noticed that the switch to DST using this library takes place one week late. I made a change which causes the change to occur on the proper date. Not sure if it's just something I'm doing or if it's actually a code issue but the following change to ntp.cpp fixed it for me.

Change: time_t beginDST = nextSunday( makeTime(tm) );
to: time_t beginDST = previousSunday( makeTime(tm) );