disable savepoints by default, added dedicated getter/setter to enable/disable, added exceptions when trying to use savepoints when not supported by the platform

disable savepoints by default, added dedicated getter/setter to enable/disable, added exceptions when trying to use savepoints when not supported by the platform

DBAL-54 - Fix sequence drop executed before tables, however sequences mostly depend on tables. Also clean up several test-failures on MSSQL tests and  Oracle Index detection.

DBAL-50 - Explicitly add an index for each foreign key added to a Schema\Table instance. Removed code to FixSchema based on foreign keys, since assumptions now dont apply anymore. Refactored algorithms to check for duplicate or potential overrule indexes into Schema\Index classes, added tests and unified Table API handling these conflicts

Fix bug in Oracle Schema/Platform detection of DateTime vs DateTimeTz type and disable a logging test that breaky MySQL testsuite.

DBAL-39 - Changed SQLLogger again, the recent change disallows to log a failed query, however adding a lastexecuted query would add additional overhead (last params and types would be needed to). So now each logger has a startQuery() and a stopQuery() method. Additionally the logger now gets passed the array of types.

DBAL-37 - Fix PostgreSQL Platform not supporting changes in Autoicnrement during ALTER TABLE generation

DBAL-33 - Added flexible DateTime type that can be used as replacement when variable date/time parts are returned from the database, for example with PostgreSQL TIMESTAMP(n) and TIME(n) types

Fix for both DDC-710 and  DDC-693, added many tests for null conversion and additional tests for the empty value conversion

DBAL-26 - Fix nasty bug with null values in Date, DateTime, DateTimeTz and Time fields introduced with the DBAL-22 fix