make schema visit namespaces
#657 - Fixed single quote in comments
#657 - add note about the intention of platform's string literal quotation method
#657 - add dedicated unit test case for AbstractPlatform::getStringLiteralQuoteCharacter()
#657 - make unit test cases for quoting string literals easier extendable
Merge branch 'jibriss-fix-postgresql-comment'
Close #657
fix SQLite integer type primary autoincrement columns
Merge pull request #666 from deeky666/DBAL-924

[DBAL-923] [DBAL-924] Fix SQLite integer type primary autoincrement columns
Merge pull request #664 from deeky666/DBAL-669

[DBAL-669] Make schema visit namespaces