Add schema changes for length for postgres

Added exit code for dbal:reserved-words command

Delete always content from table master_slave_table between tests.

Removed Unsigned Integer Support in SQL Server

Optimize autoload prefix in composer.json

Fix dropping foreign key multiple times with test

In some cases the Comparator class returns multiple drops for the same foreign key.
Specifically, in case you have two tables, A & B, with A having a foreign key FK
referencing B, if you drop table B, the resulting diff shows this FK twice,
once on the diff->orphanedForeignKeys array as we're deleting B, and another on
the diff->changedTables array as table A is also being modified. As a result of this you
get the DROP FOREIGN KEY instruction twice in the final SQL.

By having more specific autoload prefixes it is possible to reduce the number of stat calls made.

fix some phpdoc

[DBAL-335] Fix nasty bug in MasterSlaveConnection, connecting and writing to slave when using keepSlave option.

Set default session value for NLS_NUMERIC_CHARACTERS (Bugfix for DDC-2013)

Change default MySQL table collation to utf8_unicode_ci

params not passed from execute to logger

When parameters are passed to Doctrine\DBAL\Statement::execute, they are not passed to any enabled logger(s).

Default table collation changed to `utf8_unicode_ci`, as it handles properly a much wider array of characters (Cyrillic, for example) at a generally negligible cost of performance.

Bugfix DDC-2013 - Default Session Value ".," for "NLS_NUMERIC_CHARACTERS". This is needed because Oracle uses other characters for decimal separation depending on the servers locale

Fixed mini-typo

Small test fixes for PostgreSQL

Based on whether we are on 32 or 64 bit platform, postgres will return a string or an int for the expected php type of a bigint that is > 32 bits.