Fixes#507
The scanUnixLine function was erroneously returning empty lines when EOF
was reached.
This commit adds a test for the problem and changes the scanUnixLine
function to elide the trailing \n if no content was read.
Added a test for the failure.
Most of the scanner code looks like it's a modified version of
bufio.ScanLines, so I changed it to use that but always add a line feed.
Mitchell Hashimoto
Matthew Hooker