remove dartdoc's dep on package:quiver

[devoncarew]

• remove dartdoc's dep on package:quiver
• add some import prefixes to make more clear which packages we import but that we only use a method or two from
• expand the supported version range for package:cli_util

@srawlins - this PR is a bit speculative. In dartdoc we're importing package:quiver - a fairly large package - but only using a very small bit of its API. I'd definitely welcome your thoughts here -

[devoncarew]

I'm not sure why, but the travis builds for dartdoc aren't completing for me:

dart2-dartdoc_integration_test.dart: 14:05 +3 -10: Invoking command-line dartdoc (tearDownAll) [E]
dart2-dartdoc_integration_test.dart:
dart2-dartdoc_integration_test.dart:   TimeoutException after 0:12:00.000000: Test timed out after 12 minutes.
dart2-dartdoc_integration_test.dart:
dart2-dartdoc_integration_test.dart:   package:test_api/src/backend/invoker.dart 316:28  Invoker._handleError.<fn>
dart2-dartdoc_integration_test.dart:   dart:async/zone.dart 1182:47                      _rootRun
dart2-dartdoc_integration_test.dart:   dart:async/zone.dart 1093:19                      _CustomZone.run
dart2-dartdoc_integration_test.dart:   package:test_api/src/backend/invoker.dart 314:10  Invoker._handleError
dart2-dartdoc_integration_test.dart:   package:test_api/src/backend/invoker.dart 270:9   Invoker.heartbeat.<fn>.<fn>
dart2-dartdoc_integration_test.dart:   dart:async/zone.dart 1190:13                      _rootRun
dart2-dartdoc_integration_test.dart:   dart:async/zone.dart 1093:19                      _CustomZone.run
dart2-dartdoc_integration_test.dart:   package:test_api/src/backend/invoker.dart 269:38  Invoker.heartbeat.<fn>
dart2-dartdoc_integration_test.dart:   dart:async-patch/timer_patch.dart 18:15           Timer._createTimer.<fn>
dart2-dartdoc_integration_test.dart:   dart:isolate-patch/timer_impl.dart 397:19         _Timer._runTimers
dart2-dartdoc_integration_test.dart:   dart:isolate-patch/timer_impl.dart 428:5          _Timer._handleMessage
dart2-dartdoc_integration_test.dart:   dart:isolate-patch/isolate_patch.dart 168:12      _RawReceivePortImpl._handleMessage
dart2-dartdoc_integration_test.dart:
dart2-dartdoc_integration_test.dart:
dart2-dartdoc_integration_test.dart: 14:05 +3 -10: Some tests failed.
dart2-dartdoc_integration_test.dart:
dart2-dartdoc_integration_test.dart:
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#build-times-out-because-no-output-was-received

[srawlins]

Haha I had the same thing with Travis this morning. :( Something with 2.9.0 final perhaps.

[srawlins]

Each time I tried to remove the lazyConcat code, dartdoc got markedly slower :( It seems super weird. Have you benchmarked this PR? I just used time and a package like camera.

[devoncarew]

I haven't tried benchmarking this, but this is the exact impl. of concat() from quiver.

[srawlins]

Ah, I see now. I love it. Love the new tests.

[devoncarew]

Thanks! I'll circle back to this in a bit - just want to validate that the CI failures aren't related to the work in this PR.

[devoncarew]

Closing in favor of #2305.