refactorings, a bug fix (#786) and improved performance for the hydration of results from polymorphic queries.

Moved Doctrine_Migration_Builder and Doctrine_Import_Builder to Doctrine_Builder_Migration and Doctrine_Builder_Record. Updated code to work with new class names.

reverting the reorganization done in 3455-3456 in order to make merging my experimental branch to trunk easier.

Preparation for new organization of code in to sub packages. Changed autoload() to work with new structure.

Refactorings for schema files and Doctrine_Record builder. More to come but got held up on some things that zYne- must fix first.

Changed loadModels() once again. Removed loading of models based solely on model filename. Added support for different models with the same file names. All models files are required, in order to determine class names. The changes result in an overall increase in flexibility with respect to model file names.

Introduced a new attribute ATTR_AUTOLOAD_TABLE_CLASSES that can be used to control whether Doctrine should try to autoload custom table class files when looking for them.

Consolidated a few things. Initial entry of Inflector class. Moved some methods from Doctrine base class to Doctrine_Lib and Doctrine_Inflector.

Added isValidModelClass() static method and fixed getLoadedModels() in order to resort back to the (classical) approach of class inclusion as a fallback when record classes have different names than their file names. The fallback behaviour of getLoadedModels() is now similar to what is was before the changes introduced in rev 3002.