- remove debug statements
- fix render_liens() to filter any None (deleted!) lines from it's output
- make sure we insert multiple lines in proper order and that we end up with a current_line that puts us at the last line we inserted
- when doing an insert we don't actually know what the line number will be so don't pretend
- next_line() blows up (correctly) so update current_line directly
- style changes
- inserting multiple lines is actual one insert and then multiple appends; this helps ensure our current_line ends up in the correct spot