Group by file

[Nodd]

Group results by file, then by functions, instead of the actual behavior o grouping by function only ?
It could be useful when profiling lots of functions in different files, but it can be annoying since it adds another layer to expand/collapse.

It could be an option in the application settings.
It could group only if there is multiple functions in the file, and let the other functions alone.

[Nodd]

It will mess up with #18 if the numer of @profile decorators changes between runs. Still doable, but trickier.