Initial 2.0 stable release.

• The package has been renamed from Sql_Query to SqlQuery, in line with the new Aura naming standards.
• Now compatible with PHP 5.3!
• Refactored traits into interfaces (thanks @mindplay-dk).
• Refactored the internal build process (thanks again @mindplay-dk).
• Added Select::leftJoin()/innerJoin() methods (thanks @stanlemon).
• Methods bindValue() and bindValues() are now fluent (thanks @harikt).
• Select now throws an exception when there are no columns selected.
• In joins, the condition type (ON or USING) may now be part of the condition.
• Extracted new class, Quoter, for quoting identifer names.
• Extracted new class, AbstractDmlQuery, for Insert/Update/Delete queries.
• Select::cols() now accepts colname => alias pairs mixed in with sequential colname values.
• Added functionality to map last-insert-id names to alternative sequence names, esp. for Postgres and inherited/extended tables. Cf. QueryFactory::setLastInsertIdNames() and Insert::setLastInsertIdNames().