Total rewrite for DQL alias model: now using short aliases instead of long aliases (needed for Oracle portability). 

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fixed declaration of Doctrine_Connection_Pgsql::modifyLimitQuery and Doctrine_Connection_Common::modifyLimitQuery to be the same

Removed getState() and concat() methods from mysql driver, getState() is not needed (it resides at transaction class) and concat is located at mysql expression driver

Both default to TRUE. If set to false, you need to explicitly specify "length" and/or "type" in the parameter of hasColumn that specifies the validators for that column.