Most of the remaining widget examples are actually manual tests. This patch
moves them into //dev/manual_tests. A couple are examples of using services,
which I've moved to //examples/layers/services. The remainder are out-dated and
are removed by this patch.

Using local paths ensures that each package sees each other package at HEAD.

sky_engine is now at 0.0.45
sky_services is now at 0.0.45
flx is now at 0.0.4
flutter is now at 0.0.15
flutter_sprites is now at 0.0.12

sky_engine is now at 0.0.44
sky_services is now at 0.0.44
flx is now at 0.0.3
flutter is now at 0.0.14
flutter_sprites is now at 0.0.11

Also, fix warnings in rendering/sector_layout.dart
Also, fix hit testing in rendering/sector_layout.dart
Also, add WidgetToRenderBoxAdapter
Also, make the rendering library debugging tools more resilient to
dumping stuff before layout is complete.

We can build Fitness again now that playfair has been updated to account for
the package:flutter rename.