Database: SqlLiteral can be used for every aspect of database\table\selection (select, where, group by, order by, etc; except offset/limit) + tests

Database: SqlLiteral can be used for every aspect of database\table\selection (select, where, group by, order by, etc; except offset/limit) + tests

Moreover two properties have been added to SqlLiteral:
- bool $delimitable = false: whether sql builder will try to delimit literal
- bool $examinable = false: whether sql builder should examine literal while creating table joins (in some cases sql builder creates joins from subqueries which may be undesirable)