2006-05-22 - SOS refactoring almost finished

All tests are green, the refactoring of the SOS is almost finished. The interface for the usage of an RDBMS is now encapsulated inside the DBI (database interface) which is part of the Common Smalltalk Library. The DBI is intended as a Squeak counterpart to JDBC, ODBC or the DBI of Python or Perl. So other applications can use the idea of a common interface to different RDBMS too. Currently simple strategies for PostgreSQL and SQLite are implemented.