Suggestion: Improve the summary mode

[fgimian]

Hey there, thanks so much for this great tool! 😄

I think it would be great to further improve the -summary mode to show some more information. As an example, here's the coverage report in Python with coverage.py:

Name                      Stmts   Miss  Cover   Missing
-------------------------------------------------------
my_program.py                20      4    80%   33-35, 39
my_other_module.py           56      6    89%   17-23
-------------------------------------------------------
TOTAL                        76     10    87%

In particulary, it would be great to see what lines were missed in the summary.

Thanks heaps
Fotis