Fix: property access is not allowed yet

Fixes the warning emitted by mysqli when sqlstate is not set (yet?).
http://git.php.net/?p=php-src.git;a=blob;f=ext/mysqli/mysqli_prop.c;h=2d36336372b75922bd8fbf40c5c9054a5230c8a0;hb=HEAD#l36

Warning masks actual connection error.

[DBAL-474] Fix filtering sequence names on PostgreSQL

Fix DateTimeTz type compatibility on SQL Anywhere versions < 12

Fix FOR UPDATE SQL on SQL Anywhere

[DBAL-801] Add date arithmetic interval methods for seconds, minutes, weeks, quarters and years

Close #598

Adding doctrine-dbal to composer.json and making it work just like doctrine command (from Doctrine ORM)

Remove @param tags that add no value

Add missing imports

Remove type hint template clutter

Minor cleanup in SchemaManagerFunctionalTestCase

Removed unused field

Remove ref to class that does not exist

Remove duplicate suggest section in composer.json

[DBAL-835] Quote old column name in rename column SQL

Properly instantiate var and fix spelling

HHVM nightly and PHP 5.6 in builds

[DBAL-825] Drop default constraints before altering column type on SQL Server