Add line numbers in the output for faster spotting

Currently the only way to see the line number is to look at the stack trace. It takes some time for human eye to spot the line number from the mess so it would be a great addition if nodeunit could display the line number directly.

An idea how to accomplish this: loop through the lines of the stack trace until you hit the file that was specified in the command line "nodeunit foo.js". When you hit that line, use regular expression such as `line.exec(/(\d):\d+$/)` to match it.

Start by tracing how the nodeunit foo.js command formats failures and how stack-trace lines are parsed or displayed. Confirm the expected line-number format from the issue's proposed matching approach. Done means test failures display the relevant source line number directly, without requiring users to inspect the full stack trace.

Written by the indexing model from the issue text.