@morozov review: According to MySqlPlatform::getListTableColumnsSQL(), the default column is always selected. Removed ??

#2815 don't require `ssl_key` and `ssl_cert` to use `ssl_ca`

Fixes: https://github.com/doctrine/dbal/issues/2815

Fixes custom type comment regex

Fixes: https://github.com/doctrine/dbal/issues/2596
Replaces: https://github.com/doctrine/dbal/pull/2679

Don't Set a Default Value on PostgreSQL SERIAL Fields

Fixes: https://github.com/doctrine/dbal/issues/2906

Serial fields already have a default value. By opting out of `notnull`
serial fields will just set the next value in the sequence.

Postgres has a `SERIAL` data type to allow shorthand for
`nextval('sequence_name')`, but DDL like this:

    CREATE TABLE example (id SERIAL)

Cannot be generated in the DBAL schema APIs.

Default value declaration for immutable types

Fixes: https://github.com/doctrine/dbal/issues/2859

Fix BC-break regarding JsonArrayType

Fixes: https://github.com/doctrine/DoctrineBundle/issues/696
Fixes: https://github.com/doctrine/dbal/issues/2880

I know, this is REALLY nasty but that was the only way I've found to
make it work properly.

And then we don't need to wait till v3 to not require comments on the
JsonType.