MatchColumn and Expression will be unified to use Expression/ExpressionTree

In this change, an determination of operator of expression is delayed
until the time of build the query.
Refactoring for tests
Add 'filter' API to SelectQuery
Fix imcompatible __div__ and __idiv__ magic-methods for Python3
Fix sometimes test failure in Python 3.3

Because, In Python3, dict.items() returns sometimes different order of values.
Multibyte support
Improve the escape of strings of queries