/sqlite3cc

- expand sqlite_error - perhaps use boost::system_error (see boost/asio/error.hpp for an example of extending system_error)

- use sqlite3_db_mutex() to provide extended error information during sqlite_error construction - see sqlite::query::step() for example

- see if we can #include "sqlite.h" in to a namespace.

	Pros:

		we better encapsulate the library

		we can reuse "sqlite3" as a namespace

	Cons:

		makes access to real sqlite stuff awkward to sqlite3cc users, but does this matter? they can't access database._handle anyway!

		potential incompatibility when linking to libraries that also link against sqlite

- add immediate_transaction

- fix step() inconsistency - query::step() returns a row, whereas basic_statement::step() and command::step() return an int return code

- fix row/query compilation dependency issue. break dependency of querys on rows

	- can't use "row"s in the iterator

	- could wrap rows, and use dereference operator to access

	- could use a base class, which wouldn't cause extra dereferences in use and shouldn't have much overhead (no vfpt)

	- look at the boost::iterator_facade interface - can we switch to "row *"s?

- query::prepare() isn't being called during construction (form

	basic_statement's constructor)