This is necessary because pdo_sqlsrv still has some little bugs that
prevent it from being used in all use-cases. Additionally only sqlsrv
can make use of the Azure federations features.

[DBAL-204] Sane refactoring of the previous idea. Removed a bunch of code again and implemented proper schema namespacing. Also got the wording right (hopefully) and fixed the algorithms.

[DBAL-195] Fix AbstractSchemaManagertests/Doctrine/Tests/DBAL/Functional/Schema/SchemaManagerFunctionalTestCase.phpdropAndCreateSequence

[DBAL-195] Fix AbstractSchemaManagertests/Doctrine/Tests/DBAL/Functional/Schema/SchemaManagerFunctionalTestCase.phpdropAndCreateSequence

These are internal, automatically-created and shouldn't be considered part of
the schema. They cannot be recreated because of their reserved names.

DDC-887 - Fix problem with MySQL renaming of foreign keys columns. The FK has to be dropped, then column renamed, then readded

[DBAL-42] Add support to reverse engineer Comments from MySQL, PostgreSQL and ORacle into Doctrine\DBAL\Schema\Column instances and added comment comparison into Comparator.

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

DBAL-11 - Changed Interface of SQLLogger to allow for timing variables, added tests for logging. Contract of Loggers changed, they are not called before the query but after the query they are logging, which means queries that fail wont appear in the logs.