Without the command line interface to sqlite3, there is no easy method
of extracting a database into an SQL dump file.  This creates a problem
should a user want to create an in-memory database (which is useful for
a performance boost) and then save the data for later use.  It also
would be useful should the sqlite3 command not be installed.

The attached patch implements this feature as a method of the Connection
class.

thanks!

committed to trunk in r62000.

and r62012 which adds the dump.py files I forgot to svn add in r62000.

although closed, i'm assigning this to ghaering so that he knows it went
in and can merge this back into pysqlite if its not already in there.

Thanks so much.