Address referee feedback about the software package itself from our
JSS submission.  Specifically:

* Make Descriptor and EnumDescriptor objects subsettable.

* Add length() method for Descriptor objects, returning the number of
  fielddescriptors, nested type descriptors, and enum descriptors
  defined in the descriptor.

* Add names() method for Message, Descriptor, and EnumDescriptor
  objects.

* Clarify order of returned list for descriptor objects in as.list
  documentation.

* Correct the definition of as.list for EnumDescriptors to return a
  proper list instead of a named vector.

* Update the default print methods to use cat(.., fill=TRUE) instead
  of show() to eliminate the confusing [[1]] since the classes in
  RProtoBuf are not vectorized.

* Add unit tests for some of the above.



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rprotobuf@895 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
Fix test now that as.list(enumdescriptor) now correctly returns lists.



git-svn-id: svn://svn.r-forge.r-project.org/svnroot/rprotobuf@896 edb9625f-4e0d-4859-8d74-9fd3b1da38cb