Modified exception classes, new method for connection exceptions getPortableCode(), refactored some classes

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Doctrine now works seamlessly in multi-connection environment where connections are bound to classes

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

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.

Added new exception classes, renamed Doctrine_Repository to Doctrine_Table_Repository, refactored many classes

Ticket: 134

Ticket: 125

- Lazy connections possible through Doctrine_Manager::addDSN($dsn, $connectionName). Connections will then be opened automatically when they are requested the first time.

Changes concerning multiple connection control:
- injection of the Connection object into the Doctrine_Table constructor, instead of a static lookup.
- added optional Connection parameter to save/delete of Doctrine_Record and Doctrine_Collection

removing the closing PHP tags form all php files, it\'s not needed and can break sessions which are whitespace sensitive

when using Doctrine::compile(), having the require_once()'s in the source files will break things. This is because the file hasn't been included, but the class has been defined in the compiled file.  This means you have to rely on autoload to allow compile to function (or strip out all require_once's from the code on compile, but atleast one needs to be maintained). IMPORTANT: you MUST now use autoload.

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