Quoting table name

[DBAL-374] Fix asset identfier quotation

Quoting table name to avoid errors with:
SELECT * FROM order;

Correcting reference to VarDateTimeType class.

[DDC-2470, DDC-2441] Use column name instead of alias to modify order by clause

VarDateTime is replaced by correct VarDateTimeType class.

Fix an instance of doubled words in the docs

Delete unnecessary "use PDO" statement

DBAL-522 - SQLParserUtils always throws exceptions on null bound params

Demonstrates that NULL parameters are handled incorrectly by the sql parser utils as of 2.3.4

Fixed generated sql for postgres substring function