Added chapter "Transactions"
Added chapter "Queries"
Added chapter "Collections"
Add pony.__version__ attribute
Change pony version 0.4.9 -> 0.5-beta
Minor syntactic fix: replace all <> to !=
Renaming: query._cache -> query._session_cache
Improved query.exists() method
Proper query cloning: now query.filter() produces new query instead of previous query modification
Refactoring of Query._process_lambda()
Refactoring: get_lambda_args(func) function extracted
Refactoring
Local variable renaming
Local variable renaming: lambda_expr -> lambda_ast
Fixes #34: Now query.filter() lambda argument names can be different from original query names
Bug fixed: now each new query.order_by() call adds expressions to the beginning of the ORDER BY section
Query.for_update() bug fixed: now orm does not send duplicate FOR UPDATE queries
Query.order_by(None) fixed
Closes #20: Support for query.filter(**kwargs) added
Now query can be reused between db sessions