debug: show now groups code by line number. Fixes #79.
debug: show now groups code by line number. Fixes #79.

This makes show far more useful, as one can easily see what code results from
a particular line number. This makes it easier to see if the wrong code is
being generated by something, helping to identify problems faster. Also, it's
pretty neat looking.

FascinatedBox/lily,jesserayadkins/lily,FascinatedBox/lily,jesserayadkins/lily,FascinatedBox/lily,jesserayadkins/lily,FascinatedBox/lily