v0.4.15: file.imports() pulls in all transitive dependencies (#76)

this PR fixes two bugs related to file.imports() and simplifies pulling in a file's dependencies

- file.imports() will now pull in all transitive dependencies, rather than just immediate dependencies
- file.imports() correctly pulls in all immediate dependencies via file.descriptor.GetDependency() removing the need to check a file's messages and services for additional imports
- updates go vet command and go version https://golang.org/doc/go1.12#vet

v0.4.14

Handle recursive dependencies (#71)

v0.4.13: Enable BiDi graph building (#70)

* Enable BiDi graph building

v0.4.12

proto: implement Stringer interface on proto{syntax,label,type} (#58)

v0.4.11: include file dependencies in imports

include file dependencies in imports (#59)

v0.4.10: Cache entity's FQN (#57)

* cache fqn

* tests

v0.4.9: include extensions in accept() (#53)

* add extensions to accept

* test

v0.4.8: [IDL-324] Add extensions to PG* (#52)

* getting started

* add some tests

* addExtension method

* missing tests

* linting

* more stuff

* file/message/node tests and some AST stuff

* glide up

* tests for extension implementation

* glide up again

* feedback

* i broke everything :/

* y wont u hydrate :O

* slowly fix things

* fixed?

* testdata done

* tests

* assert len

* one more test

v0.4.7: Build AST from FileDescriptorSet (#48)

* Build AST from FileDescriptorSet

* checkpoint

v0.4.6

AST: special case packageless (root) entity FQNs (#47)