Added default values to migrate2utf8.xml, for any varchar and text field types, if the default values for these fields were not defined as '' in the MySQL table creation script.
Committed by vyshane
because generalcomment and teachercomment were not null and didn't have defaults.
for some reason mysql allows this but postgres complains. I've set empty string defaults and added into mysql for consistency.
by Ray Kingdon.
Works quite well, but it's not clear yet if this will be part of
major releases (due to the overlap with assignments and workshops
and the confusion this may cause).