Add proto_generator Support for Enum Name Annotations (#93)
Add proto_generator Support for Enum Name Annotations (#93)

* Fix protobuf enumeration naming per style guide.

  * (M) ygen/codegen_test.go
  * (M) ygen/genstate.go
  * (M) ygen/protoelements.go
  * (M) ygen/protoelements_test.go
  * (M) ygen/protogen.go
  * (M) ygen/protogen_test.go
    - Update protobuf output such that naming is per the style guide.
  * (A) ygen/testdata/proto/proto-enums.enums.formatted-txt
  * (A) ygen/testdata/proto/proto-enums.formatted-txt
  * (A) ygen/testdata/proto/proto-enums.yang
  * (M) ygen/testdata/proto/proto-test-c.proto-test-c.elists.elist.formatted-txt
  * (M) ygen/testdata/proto/proto-test-c.proto-test-c.entity.formatted-txt
  * (M) ygen/testdata/proto/proto-test-c.proto-test-c.formatted-txt
  * (M) ygen/testdata/proto/proto-test-e.uncompressed.proto-test-e.animals.animal.formatted-txt
  * (M) ygen/testdata/proto/proto-test-e.uncompressed.proto-test-e.foos.foo.formatted-txt
  * (M) ygen/testdata/proto/proto-test-e.uncompressed.proto-test-e.formatted-txt
    - Update test data.

* Add support for annotating original YANG enumerated value names.

  * (M) proto/yext/yext.proto
    - Add new enum field option extension allowing annotation of enum
      values with their original name.
  * (M) ygen/codegen.go
    - Add new flag to specify whether annotation should be allowed.
  * (M) ygen/codegen_test.go
    - Tests added.
  * (D) ygen/profile.out
    - Remove erroneous file.
  * (M) ygen/protogen.go
  * (M) ygen/protogen_test.go
    - Support for annotating enum fields.
  * (A) ygen/testdata/proto/proto-enums-addid.enums.formatted-txt
  * (A) ygen/testdata/proto/proto-enums-addid.formatted-txt
  * (A) ygen/testdata/proto/proto-enums-addid.yang
    - New test case for annotation of fields.
    - New test case checking that adding to an identity does not mean
      that tag values change in enums.
  * (M) ygen/testdata/proto/proto-enums.enums.formatted-txt
  * (M) ygen/testdata/proto/proto-test-d.uncompressed.enums.formatted-txt
  * (M) ygen/testdata/proto/proto-test-e.uncompressed.enums.formatted-txt
    - Fix test cases for new changes.

* Fix vet issues.

  * (M) ygen/protogen_test.go
    - Fix vet issues.

* Fix vet issues.

  * (M) ygen/protogen.go
    - Fix vet issues.

* Address review comments.

  * (M) docs/yang-to-protobuf-transformations-spec.md
    - Add description of how enum names are stored in the
      output protobuf.
  * (M) ygen/codegen.go
  * (M) ygen/protogen.go
    - Fix review comments.

* Add flag to proto_generator to allow schema name annotation.

  * (M) proto_generator/protogenerator.go
    - Add flag.

openconfig/ygot,openconfig/ygot