[I18n] Defining languages with locality (eg. en_GB) breaks functionality with SQL Integrity error - fix included

When defining languages as language_COUNTRY codes (supported by symfony by default), the functionality to work with I18n records breaks, resulting in "SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry" errors.

The reason is very simple: Doctrine's I18n language column is defined as a CHAR(2), thus shortening eg. "en_GB" value to "en", thus causing the above SQL error when a "en" translation for a record already exists.

The solution is even simpler: change the column's length to 7 in the Doctrine_I18n class's options: I've tested this and all runs great: the correct SQL is being generated, the models behave correct, ...