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

[2.0] DDC-312 -  Refactored View support of all platforms a little - Oracle now also supports the retrieval of the sql used to generate a view so that a common datastructure View is a viable option.

[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] DDC-169 - Stripped case handling since its just a load of complex crap and doesn't solve any problem! Idea: just implement case-insensitivity in the comparator.

[2.0] DDC-169 - Introduced handling of schema / database case-sensitivity differences and to allow compability between different platforms.

[2.0] DC-169 - New method AbstractSchemaManager::createSchema() which creates a schema instance with full tables and sequences, additionally listTables() was rewritten to return a full Table instance instead of just the table names.

[2.0] DDC-169 - Converted introspection queries of all platforms to return Column, Sequence, Index, ForeignKey Schema Instances instead of arrays, heavily pimped Oracle support thereby.

[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 - Added DropSchemaSql Visitor - Refactored Visitor package a bit, however its still not very appealing to have that much use statements cluttered in the code

[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...