code tidy up
Merge remote-tracking branch 'upstream/master'
tidy up null value tests and avoid mymysql and postgres drive time handling
fixed wrong logic in tests
implemented forward scrolling resultset and updated Session.Iterator() implementation
add testScroll test
comment Iterator public methods
add TODO comments
change Iterator struct naming to 'Rows' and making compatible interface to sql.Rows
update API comments
code tidy up
Merge pull request #37 from nashtsai/scrolling-rs

Scrolling rs