Added getters to AST. Removed Production::__call. Added visitor support to AST. (guilherme: dont shoot me yet :-). visitor support doesnt hurt even if we do not use it for SQL generation). Lots of other things.

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.

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

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

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