Put the responsibility to give the default schema name from CreateSchemaSqlCollector to the Platforms (abstract, sqlserver, postgresql)

Decimal column Update if precision or scale was changed

- Fixed docblocks
- Removed return statements on void methods
- Cleaned up unused private / local variables
- Fixed license issues
- Removed SVN leftovers
- Fixed doctrine-project.org links
- Added line breaks before return statements

Add getGuidExpression() to PostgreSqlPlatform so that UUID support
works properly

DBAL-54 was fixed in commit 3d55dc8e by
changing SQL queries order. However it was later reintroduced.

This patch uses a different, more future-proof way, approach by using
DROP SEQUENCE ... CASCADE syntax, and thus does not depend on queries order.

http://www.postgresql.org/docs/8.2/static/functions-net.html

[DBAL-211] Fix bug with elements in default schema not filtered for really being in the default search path.