Improve driver exception code conversion

[DBAL-543] Fix OCI8 TNS connect descriptor / Add pooled option to PDO_ORACLE

[DBAL-464] Fix dropping primary key with autoincrement column in MySQL

[DBAL-702] Add sslmode connection option to pdo_pgsql driver

Added some mysqli documentation.

phpdoc in Table::addForeignKey() update

Fix binding LOB values in mysqli driver prepared statement

HHVM compatibility: implement declared interfaces

Added some documentation for the drizzle driver.

realpath return false when using the script in a phar file.

Applying suggestions.

[DBAL-400] Fix adding primary key during table alteration in MySQL

Fix mysqli driver options

[DBAL-683] Fix link to known vendor issues in documentation

Save one columns iteration in Comparator::diffTable