[2.0] DDC-312 - Revert annoying View and Trigger variables in Schema instance, complete "View" support by just returning a View instance

[2.0] Refactored Doctrine\DBAL\Schema API a bit Table::createColumn() was inconsistent with all the other methods being add*

[2.0] DDC-169 - Further refactorings, schema max identifier length is now used for asset generation. Added platform-wide test for unique index generation with create table.

[2.0] Fixed PHP Notice in SchemaTest (only variables should be passed by reference...) and a few other cosmetics in various parts.

[2.0] DDC-169 - Savepoint for Refactorings in Schema-Tool - It is now generating DDL according to the old and the new mechanisms in parallel. Equality of generation has been verified on Sqlite, Mysql, Oracle. If Postgres is also verified, the old code will be removed in favour of the new one completly.

[2.0] - DDC-169 - Began refactoring of DBAL code, introduced object notation for a database schema, including Tables, Indexes, Constraints, Sequences and Columns. Added a CreateSql Visitor which transforms a schema object graph into the required SQL statements to create it. Next: Replacing SchemaTool::getCreateSql() with new syntax...