DDC-1266 - Fixed bug where one sequence is dropped multiple times and extended that logic to tables and constraints

Fix for DBAL-158, double precision not working with sqlite.

DDC-1337 - MySQL commits transaction on DROP TABLE, need DROP TEMPORARY TABLE. Added tests, looks like oracle commits transactions on CREATE TEMPORARY TABLE. I dont know how to fix it.

Patch for OCI8Statement to support param[0] being null. Switched isset to array_key_exists. Added test that demonstrates the bug and confirms the fix.

DBAL-132 - Make Table::addUnnamedForeignKeyConstraint() generate a name based on the input, @deprecated addUnnamedForeignKeyConstraint and addNamedForeignKeyConstraint.