Fix instance_get() to know columns without DictCursor

DictCursor doesn't work completely as it only prefixes the column
names with the table if the column is a duplicate (exists in another
table we're querying).

We have no way to know what columns go with with tables without querying
for tables when we connect.  Because we have to do this, we also no
longer need DictCursor and the turning into objects is a bit more
simple.

Also added a stupid instance_get_all() which now works.