DBAL-112, DBAL-113 - Implement AbstractPlatform::getAlterSequenceSQL() and fix comparator code for sequences

Fix bug in DropSchemaSQLCollector dropping tables before sequences which can cause constraint errors

DBAL-91 - Fix auto-generation of asset names (foreign keys and indexes) which could lead to exceptions due to auto-quoting of PostgreSQL for example. Now hashing the names with crc32+dechex

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

Temporary fix for issues appearing due to DBAL-2 reopening, found an actual additional bug that is now fixed in PostgresSQL Schema Manager

Fix change to Postgresql NULL Column detection

Temporary fix for issues appearing due to DBAL-2 reopening, found an actual additional bug that is now fixed in PostgresSQL Schema Manager

DBAL-18 - Fixed SchemaDiff to not generate a create table statment with foreign keys for platforms that doesn't support them

[2.0] Code cleanups. Preparations for DDC-193. Fixed DDC-399, type configuration remains global for now but the irritating instance methods on the Configuration have been removed. Use Type::addType et al. Added TODOs for naming standards.

[2.0] DDC-396 - Fixed bug with RESTRICT/NO ACTION and PHP NULL not valued as the same in Schema Foreign Key Diff

[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-200 Implemented support for @columnDefinition - even with support to pass the definition to join columns if necessary for relations.

[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 - AbstractPlatform::getAlterTableSql() now accepts only a TableDiff instance as argument across all platforms.