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

[DBAL-843] Fix reverse engineering LOB type column types in MySQL

Fix integer 0 default value reverse engineering on SQL Anywhere

Fix reverse engineering quoted table names on PostgreSQL

Fix type hint

Change weird way of adding an entry to SplObjectStorage

[DBAL-834] Fix order by with aggregate function(s) for limit/offset queries on SQL Server

Remove unused imports

Fix driver exception conversion for newer SQLite versions

Fix FQNs

Improve param name

Add missing @param tags

Don't return the return values of methods that do not return anything

Fix incorrect reference to PDO in DB2Statement

Fix incorrect type hint in TableDiff

Remove plain wrong type hint where none is needed to begin with

Get rid of weird ternary statement

Various doc imporvements in Index