Define tables outside opDB

Currently, opDB has `target` & `guide_stars` table which were expected to contain all science and guide candidate targets to be observed. Pull them out of opDB to somewhere maintained by someone (probably NAOJ). Related tables such as `proposal` & `program` may be out of opDB and related to the queue-related database. On the other hand, we should track records of observed targets and observing status, so we need to think about new tables for the purpose. The first action would be sorting out the candidate tables and making a list.