Apply `--scope-output` filters after `getSourceReport`

[liamappelbe]

The --scope-output filters are passed to getSourceReport.libraryFilters, but there are cases where the report can contain ranges that bypass the filter. This happens when the range has a different library than their enclosing function/class (eg mixins).

To fix this we just need to re-apply the filters to the reported ranges. It's still important to pass the filters to getSourceReport, because these are pretty rare edge cases and the filtering is still a useful optimisation to reduce the size of the report.

Fixes #495

[coveralls]

coverage: 93.74% (+0.04%) from 93.698% when pulling 6ce09b9d8d747217cd0d21386541e5f2599bc90c on fix495 into f2e52fb3f686e488fb6f846b0f78f41d339a28ba on master.