This change is to make applications who define they own message format (without metadata inspection and coercion) to easily create its IMessageMetadata.
1. Never allocate empty statement - always use att->prepare() to create statement interface
2. Separated IStatement into 2 parts - statement itself and resultset.
3. Added stmt->openCursor() (and att->openCursor() for unprepared statements) to create IResultSet.
4. Always use IMessageMetadata (former IParametersMetadata) to pass message fromat info from client,
therefore avoiding need in BLR generation in client applications.
