Make methods in WithMany* classes into instance methods

They said they took $self, but they were being used as class methods.  I
would like to add a feature that actually uses them as instance methods
so I went ahead and made the users start calling them as instance
methods.
Remove unused plan files
Bring WithSampleName interface closer to WithManySampleNames
Rename method
Rename method and don't export unnecessarily
Remove unnecessary exports
Rename method
Change how per-library bam-readcount columns are reported

Add library names to vaf interpreters
Vaf interpreter returns per-library hash instead of stringifying the fields
Many sample vaf interpreter uses field names directly from single-sample vaf interpreters
Full report uses per-library field names directly from the interpreter
Tumor-only report translates per-library field names back to generic headers
MinCoverageObservedInterpreter and MaxVafObservedInterpreter get the sample-specific field names
Add per_library headers to docm report and remove unused method
Docm reporter needs library names
update docm docs to include library_names
Merge pull request #325 from apregier/per_library_headers

Vaf interpreters pass per-library fields separately to reporters