Eyport import of all table definitions

At the recent version table definitions were not exported, only the content of some selected tables. In attempt to be able to re-build an access application from scratch by this module only, I added an export routine for table definitions. I chose "create table" SQL as storage format, but ran into a yet unsolved problem with some referential integrity settings. At least the joins are there and the user is notified to make some checkmarks. Amongst the solved problems is re-establishing of references to external libraries.