Fix bugs in finding trigger time

Fix description: dict.update() returns None, but the dict is updated,
so don’t assign, just update.

Fix filling t_trigger column: getattr(table.cols, ‘’) gets the column,
but not the array of elements, so add [:].

Fix not finding trigger: first_above_threshold now returns -999,
when no trigger found, so use that instead of -1.

Disable debug messages