Add an option to change the output directory.
Add newlines to the ends of generated source files.
Use relative paths in source maps.

Also includes bonus fixes for source map error traces.
Clean up build.sh.
Support both file:line and file:line:col in firefox.

New versions of Firefox report the column number, so take advantage of
that.
Merge pull request #208 from goffrie/relative

Relative paths + other stuff